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   <hgroup><h1 class=allcaps>HTML</h1><p id=living-standard>Living Standard — Last Updated <span class=pubdate>10 September 2025</span></hgroup>
   
   

   
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  <nav><a href=introduction.html>← 1 Introduction</a> — <a href=index.html>Table of Contents</a> — <a href=common-microsyntaxes.html>2.3 Common microsyntaxes →</a></nav><ol class=toc><li id=toc-infrastructure><a href=infrastructure.html#infrastructure><span class=secno>2</span> Common infrastructure</a><ol><li><a href=infrastructure.html#terminology><span class=secno>2.1</span> Terminology</a><ol><li><a href=infrastructure.html#parallelism><span class=secno>2.1.1</span> Parallelism</a><li><a href=infrastructure.html#resources><span class=secno>2.1.2</span> Resources</a><li><a href=infrastructure.html#xml><span class=secno>2.1.3</span> XML compatibility</a><li><a href=infrastructure.html#dom-trees><span class=secno>2.1.4</span> DOM trees</a><li><a href=infrastructure.html#scripting-2><span class=secno>2.1.5</span> Scripting</a><li><a href=infrastructure.html#plugins><span class=secno>2.1.6</span> Plugins</a><li><a href=infrastructure.html#encoding-terminology><span class=secno>2.1.7</span> Character encodings</a><li><a href=infrastructure.html#conformance-classes><span class=secno>2.1.8</span> Conformance classes</a><li><a href=infrastructure.html#dependencies><span class=secno>2.1.9</span> Dependencies</a><li><a href=infrastructure.html#extensibility-2><span class=secno>2.1.10</span> Extensibility</a><li><a href=infrastructure.html#interactions-with-xpath-and-xslt><span class=secno>2.1.11</span> Interactions with XPath and XSLT</a></ol><li><a href=infrastructure.html#policy-controlled-features><span class=secno>2.2</span> Policy-controlled features</a></ol></ol><h2 id=infrastructure><span class=secno>2</span> Common infrastructure<a href=#infrastructure class=self-link></a></h2>

  <p>This specification depends on <cite>Infra</cite>. <a href=references.html#refsINFRA>[INFRA]</a></p>

  <h3 id=terminology><span class=secno>2.1</span> Terminology<a href=#terminology class=self-link></a></h3>

  <p>This specification refers to both HTML and XML attributes and IDL attributes, often in the same
  context. When it is not clear which is being referred to, they are referred to as <dfn data-lt="content attribute" data-export="">content attributes</dfn> for HTML and XML attributes,
  and <dfn>IDL attributes</dfn> for those defined on IDL interfaces. Similarly, the term
  "properties" is used for both JavaScript object properties and CSS properties. When these are
  ambiguous they are qualified as <dfn>object properties</dfn> and <dfn>CSS properties</dfn> respectively.</p>

  <p>Generally, when the specification states that a feature applies to <a id=terminology:syntax href=syntax.html#syntax>the HTML syntax</a>
  or <a id=terminology:the-xhtml-syntax href=xhtml.html#the-xhtml-syntax>the XML syntax</a>, it also includes the other. When a feature specifically only
  applies to one of the two languages, it is called out by explicitly stating that it does not apply
  to the other format, as in "for HTML, ... (this does not apply to XML)".</p>

  <p>This specification uses the term <dfn>document</dfn> to refer to any use of HTML,
  ranging from short static documents to long essays or reports with rich multimedia, as well as to
  fully-fledged interactive applications. The term is used to refer both to <code id=terminology:document><a href=dom.html#document>Document</a></code>
  objects and their descendant DOM trees, and to serialized byte streams using the <a href=syntax.html#syntax id=terminology:syntax-2>HTML syntax</a> or the <a href=xhtml.html#the-xhtml-syntax id=terminology:the-xhtml-syntax-2>XML syntax</a>, depending
  on context.</p>

  <p>In the context of the DOM structures, the terms <a href=https://dom.spec.whatwg.org/#html-document id=terminology:html-documents data-x-internal=html-documents>HTML
  document</a> and <a href=https://dom.spec.whatwg.org/#xml-document id=terminology:xml-documents data-x-internal=xml-documents>XML document</a> are used as defined in
  <cite>DOM</cite>, and refer specifically to two different modes that <code id=terminology:document-2><a href=dom.html#document>Document</a></code> objects
  can find themselves in. <a href=references.html#refsDOM>[DOM]</a> (Such uses are always hyperlinked to their
  definition.)</p>

  <p>In the context of byte streams, the term HTML document refers to resources labeled as
  <code id=terminology:text/html><a href=iana.html#text/html>text/html</a></code>, and the term XML document refers to resources labeled with an <a id=terminology:xml-mime-type href=https://mimesniff.spec.whatwg.org/#xml-mime-type data-x-internal=xml-mime-type>XML
  MIME type</a>.</p>

  <hr>

  <p>For simplicity, terms such as <dfn>shown</dfn>, <dfn>displayed</dfn>, and
  <dfn>visible</dfn> might sometimes be used when referring to the way a document is
  rendered to the user. These terms are not meant to imply a visual medium; they must be considered
  to apply to other media in equivalent ways.</p>


  

  <h4 id=parallelism><span class=secno>2.1.1</span> Parallelism<a href=#parallelism class=self-link></a></h4>

  <p>To run steps <dfn id=in-parallel data-export="">in parallel</dfn> means those steps are to be run, one after another,
  at the same time as other logic in the standard (e.g., at the same time as the <a id=parallelism:event-loop href=webappapis.html#event-loop>event
  loop</a>). This standard does not define the precise mechanism by which this is achieved, be it
  time-sharing cooperative multitasking, fibers, threads, processes, using different hyperthreads,
  cores, CPUs, machines, etc. By contrast, an operation that is to run <dfn id=immediately>immediately</dfn> must
  interrupt the currently running task, run itself, and then resume the previously running task.</p>

  <p class=note>For guidance on writing specifications that leverage parallelism, see <a href=webappapis.html#event-loop-for-spec-authors>Dealing with the event loop from other specifications</a>.</p>

  <p>To avoid race conditions between different <a href=#in-parallel id=parallelism:in-parallel>in parallel</a> algorithms that operate on
  the same data, a <a href=#parallel-queue id=parallelism:parallel-queue>parallel queue</a> can be used.</p>

  <p>A <dfn id=parallel-queue data-export="">parallel queue</dfn> represents a queue of algorithm steps that must be run in
  series.</p>

  <p>A <a href=#parallel-queue id=parallelism:parallel-queue-2>parallel queue</a> has an <dfn id=algorithm-queue>algorithm queue</dfn> (a <a id=parallelism:queue href=https://infra.spec.whatwg.org/#queue data-x-internal=queue>queue</a>),
  initially empty.</p>

  <p>To <dfn data-dfn-for="parallel queue" id=enqueue-the-following-steps data-lt="enqueue steps|enqueue the following
  steps" data-export="">enqueue steps</dfn> to a <a href=#parallel-queue id=parallelism:parallel-queue-3>parallel queue</a>,
  <a id=parallelism:enqueue href=https://infra.spec.whatwg.org/#queue-enqueue data-x-internal=enqueue>enqueue</a> the algorithm steps to the <a href=#parallel-queue id=parallelism:parallel-queue-4>parallel queue</a>'s <a href=#algorithm-queue id=parallelism:algorithm-queue>algorithm
  queue</a>.</p>

  <p>To <dfn id=starting-a-new-parallel-queue data-lt="start a new parallel queue|starting a
  new parallel queue" data-export="">start a new parallel queue</dfn>, run the following steps:</p>

  <ol><li><p>Let <var>parallelQueue</var> be a new <a href=#parallel-queue id=parallelism:parallel-queue-5>parallel queue</a>.<li>
    <p>Run the following steps <a href=#in-parallel id=parallelism:in-parallel-2>in parallel</a>:</p>

    <ol><li>
      <p>While true:</p>

      <ol><li><p>Let <var>steps</var> be the result of <a href=https://infra.spec.whatwg.org/#queue-dequeue id=parallelism:dequeue data-x-internal=dequeue>dequeuing</a> from
       <var>parallelQueue</var>'s <a href=#algorithm-queue id=parallelism:algorithm-queue-2>algorithm queue</a>.<li><p>If <var>steps</var> is not nothing, then run <var>steps</var>.<li><p><a id=parallelism:assert href=https://infra.spec.whatwg.org/#assert data-x-internal=assert>Assert</a>: running <var>steps</var> did not throw an exception, as steps
       running <a href=#in-parallel id=parallelism:in-parallel-3>in parallel</a> are not allowed to throw.</ol>

      <p class=note>Implementations are not expected to implement this as a continuously running
      loop. Algorithms in standards are to be easy to understand and are not necessarily great for
      battery life or performance.</p>
     </ol>
   <li><p>Return <var>parallelQueue</var>.</ol>

  <p class=note>Steps running <a href=#in-parallel id=parallelism:in-parallel-4>in parallel</a> can themselves run other steps in <a href=#in-parallel id=parallelism:in-parallel-5>in
  parallel</a>. E.g., inside a <a href=#parallel-queue id=parallelism:parallel-queue-6>parallel queue</a> it can be useful to run a series of
  steps in parallel with the queue.</p>

  <div class=example>
   <p>Imagine a standard defined <var>nameList</var> (a <a id=parallelism:list href=https://infra.spec.whatwg.org/#list data-x-internal=list>list</a>), along with a method to
   add a <var>name</var> to <var>nameList</var>, unless <var>nameList</var> already <a href=https://infra.spec.whatwg.org/#list-contain id=parallelism:list-contains data-x-internal=list-contains>contains</a> <var>name</var>, in which case it rejects.</p>

   <p>The following solution suffers from race conditions:</p>

   <ol><li><p>Let <var>p</var> be a new promise created in <a id=parallelism:this href=https://webidl.spec.whatwg.org/#this data-x-internal=this>this</a>'s <a href=webappapis.html#concept-relevant-realm id=parallelism:concept-relevant-realm>relevant realm</a>.<li><p>Let <var>global</var> be <a id=parallelism:this-2 href=https://webidl.spec.whatwg.org/#this data-x-internal=this>this</a>'s <a id=parallelism:concept-relevant-global href=webappapis.html#concept-relevant-global>relevant global
    object</a>.<li>
     <p>Run the following steps <a href=#in-parallel id=parallelism:in-parallel-6>in parallel</a>:</p>

     <ol><li><p>If <var>nameList</var> <a href=https://infra.spec.whatwg.org/#list-contain id=parallelism:list-contains-2 data-x-internal=list-contains>contains</a> <var>name</var>,
      then <a id=parallelism:queue-a-global-task href=webappapis.html#queue-a-global-task>queue a global task</a> on the <a id=parallelism:dom-manipulation-task-source href=webappapis.html#dom-manipulation-task-source>DOM manipulation task source</a> given
      <var>global</var> to reject <var>p</var> with a <code id=parallelism:typeerror><a data-x-internal=typeerror href=https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-typeerror>TypeError</a></code>, and abort these
      steps.<li><p>Do some potentially lengthy work.<li><p><a href=https://infra.spec.whatwg.org/#list-append id=parallelism:list-append data-x-internal=list-append>Append</a> <var>name</var> to
      <var>nameList</var>.<li><p><a id=parallelism:queue-a-global-task-2 href=webappapis.html#queue-a-global-task>Queue a global task</a> on the <a id=parallelism:dom-manipulation-task-source-2 href=webappapis.html#dom-manipulation-task-source>DOM manipulation task source</a> given
      <var>global</var> to resolve <var>p</var> with undefined.</ol>
    <li><p>Return <var>p</var>.</ol>

   <p>Two invocations of the above could run simultaneously, meaning <var>name</var> isn't in
   <var>nameList</var> during step 3.1, but it <em>might be added</em> before step 3.3 runs,
   meaning <var>name</var> ends up in <var>nameList</var> twice.</p>

   <p>Parallel queues solve this. The standard would let <var>nameListQueue</var> be the result of
   <a href=#starting-a-new-parallel-queue id=parallelism:starting-a-new-parallel-queue>starting a new parallel queue</a>, then:</p>

   <ol><li><p>Let <var>p</var> be a new promise created in <a id=parallelism:this-3 href=https://webidl.spec.whatwg.org/#this data-x-internal=this>this</a>'s <a href=webappapis.html#concept-relevant-realm id=parallelism:concept-relevant-realm-2>relevant realm</a>.<li><p>Let <var>global</var> be <a id=parallelism:this-4 href=https://webidl.spec.whatwg.org/#this data-x-internal=this>this</a>'s <a id=parallelism:concept-relevant-global-2 href=webappapis.html#concept-relevant-global>relevant global
    object</a>.<li>
     <p><mark><a href=#enqueue-the-following-steps id=parallelism:enqueue-the-following-steps>Enqueue the following steps</a> to <var>nameListQueue</var>:</mark></p>

     <ol><li><p>If <var>nameList</var> <a href=https://infra.spec.whatwg.org/#list-contain id=parallelism:list-contains-3 data-x-internal=list-contains>contains</a> <var>name</var>,
      then <a id=parallelism:queue-a-global-task-3 href=webappapis.html#queue-a-global-task>queue a global task</a> on the <a id=parallelism:dom-manipulation-task-source-3 href=webappapis.html#dom-manipulation-task-source>DOM manipulation task source</a> given
      <var>global</var> to reject <var>p</var> with a <code id=parallelism:typeerror-2><a data-x-internal=typeerror href=https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-typeerror>TypeError</a></code>, and abort these
      steps.<li><p>Do some potentially lengthy work.<li><p><a href=https://infra.spec.whatwg.org/#list-append id=parallelism:list-append-2 data-x-internal=list-append>Append</a> <var>name</var> to
      <var>nameList</var>.<li><p><a id=parallelism:queue-a-global-task-4 href=webappapis.html#queue-a-global-task>Queue a global task</a> on the <a id=parallelism:dom-manipulation-task-source-4 href=webappapis.html#dom-manipulation-task-source>DOM manipulation task source</a> given
      <var>global</var> to resolve <var>p</var> with undefined.</ol>
    <li><p>Return <var>p</var>.</ol>

   <p>The steps would now queue and the race is avoided.</p>
  </div>

  


  <h4 id=resources><span class=secno>2.1.2</span> Resources<a href=#resources class=self-link></a></h4>

  <p>The specification uses the term <dfn>supported</dfn> when referring to whether a user
  agent has an implementation capable of decoding the semantics of an external resource. A format or
  type is said to be <i>supported</i> if the implementation can process an external resource of that
  format or type without critical aspects of the resource being ignored. Whether a specific resource
  is <i>supported</i> can depend on what features of the resource's format are in use.</p>

  <p class=example>For example, a PNG image would be considered to be in a supported format if its
  pixel data could be decoded and rendered, even if, unbeknownst to the implementation, the image
  also contained animation data.</p>

  <p class=example>An MPEG-4 video file would not be considered to be in a supported format if the
  compression format used was not supported, even if the implementation could determine the
  dimensions of the movie from the file's metadata.</p>

  <p>What some specifications, in particular the HTTP specifications, refer to as a
  <i>representation</i> is referred to in this specification as a <dfn>resource</dfn>.
  <a href=references.html#refsHTTP>[HTTP]</a></p>

  <p>A resource's <dfn id=critical-subresources>critical subresources</dfn> are those that the resource needs to have
  available to be correctly processed. Which resources are considered critical or not is defined by
  the specification that defines the resource's format.</p>

  <p>For <a href=https://drafts.csswg.org/cssom/#css-style-sheet id=resources:css-style-sheet data-x-internal=css-style-sheet>CSS style sheets</a>, we tentatively define here that
  their critical subresources are other style sheets imported via <code>@import</code>
  rules, including those indirectly imported by other imported style sheets.</p>

  <p class=XXX>This definition is not fully interoperable; furthermore, some user agents seem to
  count resources like background images or web fonts as critical subresources. Ideally, the CSS
  Working Group would define this; see <a href=https://github.com/w3c/csswg-drafts/issues/1088>w3c/csswg-drafts issue #1088</a> to track
  progress on that front.</p>


  <h4 id=xml><span class=secno>2.1.3</span> XML compatibility<a href=#xml class=self-link></a></h4>

  <p id=html-namespace>To ease migration from HTML to XML, user agents conforming to this
  specification will place elements in HTML in the <code id=xml:html-namespace-2><a data-x-internal=html-namespace-2 href=https://infra.spec.whatwg.org/#html-namespace>http://www.w3.org/1999/xhtml</a></code> namespace, at least for the purposes of the DOM and
  CSS. The term "<dfn id=html-elements data-export="">HTML elements</dfn>" refers to any element in that namespace, even in
  XML documents.</p>

  <p>Except where otherwise stated, all elements defined or mentioned in this specification are in
  the <a id=xml:html-namespace-2-2 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a> ("<code>http://www.w3.org/1999/xhtml</code>"), and all
  attributes defined or mentioned in this specification have no namespace.</p>

  <p>The term <dfn id=element-type>element type</dfn> is used to refer to the set of elements that have a given
  local name and namespace. For example, <code id=xml:the-button-element><a href=form-elements.html#the-button-element>button</a></code> elements are elements with the element
  type <code id=xml:the-button-element-2><a href=form-elements.html#the-button-element>button</a></code>, meaning they have the local name "<code>button</code>" and
  (implicitly as defined above) the <a id=xml:html-namespace-2-3 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>.</p>


  <h4 id=dom-trees><span class=secno>2.1.4</span> DOM trees<a href=#dom-trees class=self-link></a></h4>

  <p>When it is stated that some element or attribute is <dfn id=ignore>ignored</dfn>, or
  treated as some other value, or handled as if it was something else, this refers only to the
  processing of the node after it is in the DOM. A user agent must not mutate the
  DOM in such situations.</p>

  <p>A content attribute is said to <dfn>change</dfn> value only if its new value is
  different than its previous value; setting an attribute to a value it already has does not change
  it.</p>

  <p>The term <dfn>empty</dfn>, when used for an attribute value, <code id=dom-trees:text><a data-x-internal=text href=https://dom.spec.whatwg.org/#interface-text>Text</a></code> node,
  or string, means that the <a id=dom-trees:length href=https://infra.spec.whatwg.org/#string-length data-x-internal=length>length</a> of the text is zero (i.e., not even containing <a href=https://infra.spec.whatwg.org/#control id=dom-trees:control data-x-internal=control>controls</a> or U+0020 SPACE).</p>

  <p>An HTML element can have specific <dfn id=html-element-insertion-steps>HTML element insertion steps</dfn>, <dfn id=html-element-post-connection-steps>HTML element
  post-connection steps</dfn>, <dfn id=html-element-removing-steps>HTML element removing steps</dfn>, and <dfn id=html-element-moving-steps>HTML element moving
  steps</dfn> all defined for the element's <a href=https://dom.spec.whatwg.org/#concept-element-local-name id=dom-trees:concept-element-local-name data-x-internal=concept-element-local-name>local
  name</a>.</p>

  <p>The <a href=https://dom.spec.whatwg.org/#concept-node-insert-ext id=dom-trees:concept-node-insert-ext data-x-internal=concept-node-insert-ext>insertion steps</a> for the HTML Standard, given
  <var>insertedNode</var>, are defined as the following:</p>

  <ol><li><p>If <var>insertedNode</var> is an element whose <a href=https://dom.spec.whatwg.org/#concept-element-namespace id=dom-trees:concept-element-namespace data-x-internal=concept-element-namespace>namespace</a> is the <a id=dom-trees:html-namespace-2 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>, and this
   standard defines <a href=#html-element-insertion-steps id=dom-trees:html-element-insertion-steps>HTML element insertion steps</a>
   for <var>insertedNode</var>'s <a href=https://dom.spec.whatwg.org/#concept-element-local-name id=dom-trees:concept-element-local-name-2 data-x-internal=concept-element-local-name>local name</a>, then
   run the corresponding <a href=#html-element-insertion-steps id=dom-trees:html-element-insertion-steps-2>HTML element insertion steps</a> given
   <var>insertedNode</var>.<li>
    <p>If <var>insertedNode</var> is a <a id=dom-trees:form-associated-element href=forms.html#form-associated-element>form-associated element</a> or the ancestor of a
    <a id=dom-trees:form-associated-element-2 href=forms.html#form-associated-element>form-associated element</a>, then:</p>

    <ol><li><p>If the <a id=dom-trees:form-associated-element-3 href=forms.html#form-associated-element>form-associated element</a>'s <a id=dom-trees:parser-inserted-flag href=form-control-infrastructure.html#parser-inserted-flag>parser inserted flag</a> is set,
     then return.<li><p><a id=dom-trees:reset-the-form-owner href=form-control-infrastructure.html#reset-the-form-owner>Reset the form owner</a> of the <a id=dom-trees:form-associated-element-4 href=forms.html#form-associated-element>form-associated element</a>.</ol>
   <li><p>If <var>insertedNode</var> is an <code id=dom-trees:element><a data-x-internal=element href=https://dom.spec.whatwg.org/#interface-element>Element</a></code> that is not on the
   <a id=dom-trees:stack-of-open-elements href=parsing.html#stack-of-open-elements>stack of open elements</a> of an <a id=dom-trees:html-parser href=parsing.html#html-parser>HTML parser</a>, then
   <a id=dom-trees:process-internal-resource-links href=links.html#process-internal-resource-links>process internal resource links</a> given <var>insertedNode</var>'s
   <a id=dom-trees:node-document href=https://dom.spec.whatwg.org/#concept-node-document data-x-internal=node-document>node document</a>.</ol>

  <p>The <a href=https://dom.spec.whatwg.org/#concept-node-post-connection-ext id=dom-trees:concept-node-post-connection-ext data-x-internal=concept-node-post-connection-ext>post-connection steps</a> for the HTML
  Standard, given <var>insertedNode</var>, are defined as the following:</p>

  <ol><li><p>If <var>insertedNode</var> is an element whose <a href=https://dom.spec.whatwg.org/#concept-element-namespace id=dom-trees:concept-element-namespace-2 data-x-internal=concept-element-namespace>namespace</a> is the <a id=dom-trees:html-namespace-2-2 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>, and this
   standard defines <a href=#html-element-post-connection-steps id=dom-trees:html-element-post-connection-steps>HTML element post-connection
   steps</a> for <var>insertedNode</var>'s <a href=https://dom.spec.whatwg.org/#concept-element-local-name id=dom-trees:concept-element-local-name-3 data-x-internal=concept-element-local-name>local
   name</a>, then run the corresponding <a href=#html-element-post-connection-steps id=dom-trees:html-element-post-connection-steps-2>HTML element post-connection steps</a> given
   <var>insertedNode</var>.</ol>

  <p>The <a href=https://dom.spec.whatwg.org/#concept-node-remove-ext id=dom-trees:concept-node-remove-ext data-x-internal=concept-node-remove-ext>removing steps</a> for the HTML Standard, given
  <var>removedNode</var> and <var>oldParent</var>, are defined as the following:</p>

  <ol><li><p>Let <var>document</var> be <var>removedNode</var>'s <a id=dom-trees:node-document-2 href=https://dom.spec.whatwg.org/#concept-node-document data-x-internal=node-document>node document</a>.<li id=node-remove-focus-fixup>
    <p>If <var>document</var>'s <a href=interaction.html#focused-area-of-the-document id=dom-trees:focused-area-of-the-document>focused area</a> is
    <var>removedNode</var>, then set <var>document</var>'s <a href=interaction.html#focused-area-of-the-document id=dom-trees:focused-area-of-the-document-2>focused area</a> to <var>document</var>'s <a id=dom-trees:viewport href=https://drafts.csswg.org/css2/#viewport data-x-internal=viewport>viewport</a>, and set
    <var>document</var>'s <a id=dom-trees:concept-relevant-global href=webappapis.html#concept-relevant-global>relevant global object</a>'s <a href=nav-history-apis.html#window-navigation-api id=dom-trees:window-navigation-api>navigation API</a>'s <a id=dom-trees:focus-changed-during-ongoing-navigation href=nav-history-apis.html#focus-changed-during-ongoing-navigation>focus changed during ongoing
    navigation</a> to false.</p>

    <p class=note>This does <em>not</em> perform the <a id=dom-trees:unfocusing-steps href=interaction.html#unfocusing-steps>unfocusing steps</a>,
    <a id=dom-trees:focusing-steps href=interaction.html#focusing-steps>focusing steps</a>, or <a id=dom-trees:focus-update-steps href=interaction.html#focus-update-steps>focus update steps</a>, and thus no <code id=dom-trees:event-blur><a href=indices.html#event-blur>blur</a></code> or <code id=dom-trees:event-change><a href=indices.html#event-change>change</a></code> events are
    fired.</p>
   <li><p>If <var>removedNode</var> is an element whose <a href=https://dom.spec.whatwg.org/#concept-element-namespace id=dom-trees:concept-element-namespace-3 data-x-internal=concept-element-namespace>namespace</a> is the <a id=dom-trees:html-namespace-2-3 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>, and this
   standard defines <a href=#html-element-removing-steps id=dom-trees:html-element-removing-steps>HTML element removing steps</a>
   for <var>removedNode</var>'s <a href=https://dom.spec.whatwg.org/#concept-element-local-name id=dom-trees:concept-element-local-name-4 data-x-internal=concept-element-local-name>local name</a>, then
   run the corresponding <a href=#html-element-removing-steps id=dom-trees:html-element-removing-steps-2>HTML element removing steps</a> given <var>removedNode</var> and
   <var>oldParent</var>.<li><p>If <var>removedNode</var> is a <a id=dom-trees:form-associated-element-5 href=forms.html#form-associated-element>form-associated element</a> with a non-null
   <a id=dom-trees:form-owner href=form-control-infrastructure.html#form-owner>form owner</a> and <var>removedNode</var> and its <a id=dom-trees:form-owner-2 href=form-control-infrastructure.html#form-owner>form owner</a> are no longer
   in the same <a id=dom-trees:tree href=https://dom.spec.whatwg.org/#concept-tree data-x-internal=tree>tree</a>, then <a id=dom-trees:reset-the-form-owner-2 href=form-control-infrastructure.html#reset-the-form-owner>reset the form owner</a> of
   <var>removedNode</var>.<li><p>If <var>removedNode</var>'s <code id=dom-trees:attr-popover><a href=popover.html#attr-popover>popover</a></code> attribute is not in
   the <a href=popover.html#attr-popover-none-state id=dom-trees:attr-popover-none-state>No Popover</a> state, then run the <a id=dom-trees:hide-popover-algorithm href=popover.html#hide-popover-algorithm>hide
   popover algorithm</a> given <var>removedNode</var>, false, false, false, and null.</ol>

  <p>The <a href=https://dom.spec.whatwg.org/#concept-node-move-ext id=dom-trees:concept-node-move-ext data-x-internal=concept-node-move-ext>moving steps</a> for the HTML Standard, given
  <var>movedNode</var>, are defined as the following:</p>

  <ol><li><p>If <var>movedNode</var> is an element whose <a href=https://dom.spec.whatwg.org/#concept-element-namespace id=dom-trees:concept-element-namespace-4 data-x-internal=concept-element-namespace>namespace</a> is the <a id=dom-trees:html-namespace-2-4 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>, and this
   standard defines <a href=#html-element-moving-steps id=dom-trees:html-element-moving-steps>HTML element moving steps</a> for <var>movedNode</var>'s <a href=https://dom.spec.whatwg.org/#concept-element-local-name id=dom-trees:concept-element-local-name-5 data-x-internal=concept-element-local-name>local name</a>, then run the corresponding <a href=#html-element-moving-steps id=dom-trees:html-element-moving-steps-2>HTML
   element moving steps</a> given <var>movedNode</var>.<li><p>If <var>movedNode</var> is a <a id=dom-trees:form-associated-element-6 href=forms.html#form-associated-element>form-associated element</a> with a non-null
   <a id=dom-trees:form-owner-3 href=form-control-infrastructure.html#form-owner>form owner</a> and <var>movedNode</var> and its <a id=dom-trees:form-owner-4 href=form-control-infrastructure.html#form-owner>form owner</a> are no longer in
   the same <a id=dom-trees:tree-2 href=https://dom.spec.whatwg.org/#concept-tree data-x-internal=tree>tree</a>, then <a id=dom-trees:reset-the-form-owner-3 href=form-control-infrastructure.html#reset-the-form-owner>reset the form owner</a> of
   <var>movedNode</var>.</ol>

  <p>A <dfn id=insert-an-element-into-a-document data-lt="inserted into a document|node is inserted into a document" data-export="">node is inserted into a
  document</dfn> when the <a href=https://dom.spec.whatwg.org/#concept-node-insert-ext id=dom-trees:concept-node-insert-ext-2 data-x-internal=concept-node-insert-ext>insertion steps</a> are invoked
  with it as the argument and it is now <a id=dom-trees:in-a-document-tree href=https://dom.spec.whatwg.org/#in-a-document-tree data-x-internal=in-a-document-tree>in a document tree</a>.  Analogously, a <dfn id=remove-an-element-from-a-document data-lt="removed
  from a document|node is removed from a document" data-export="">node is removed from a document</dfn> when
  the <a href=https://dom.spec.whatwg.org/#concept-node-remove-ext id=dom-trees:concept-node-remove-ext-2 data-x-internal=concept-node-remove-ext>removing steps</a> are invoked with it as the
  argument and it is now no longer <a id=dom-trees:in-a-document-tree-2 href=https://dom.spec.whatwg.org/#in-a-document-tree data-x-internal=in-a-document-tree>in a document tree</a>.</p>

  <p>A node <dfn id=becomes-connected data-export="">becomes connected</dfn> when the <a href=https://dom.spec.whatwg.org/#concept-node-insert-ext id=dom-trees:concept-node-insert-ext-3 data-x-internal=concept-node-insert-ext>insertion steps</a> are invoked with it as the argument and it
  is now <a id=dom-trees:connected href=https://dom.spec.whatwg.org/#connected data-x-internal=connected>connected</a>. Analogously, a node <dfn id=becomes-disconnected data-lt="become disconnected" data-export="">becomes disconnected</dfn> when the <a href=https://dom.spec.whatwg.org/#concept-node-remove-ext id=dom-trees:concept-node-remove-ext-3 data-x-internal=concept-node-remove-ext>removing
  steps</a> are invoked with it as the argument and it is now no longer
  <a id=dom-trees:connected-2 href=https://dom.spec.whatwg.org/#connected data-x-internal=connected>connected</a>.</p>

  <p>A node is <dfn id=browsing-context-connected data-export="">browsing-context connected</dfn> when it is <a id=dom-trees:connected-3 href=https://dom.spec.whatwg.org/#connected data-x-internal=connected>connected</a> and
  its <a href=https://dom.spec.whatwg.org/#concept-shadow-including-root id=dom-trees:shadow-including-root data-x-internal=shadow-including-root>shadow-including root</a>'s <a href=document-sequences.html#concept-document-bc id=dom-trees:concept-document-bc>browsing context</a> is non-null. A node <dfn id=becomes-browsing-context-connected data-lt="become
  browsing-context connected" data-export="">becomes browsing-context connected</dfn> when the <a href=https://dom.spec.whatwg.org/#concept-node-insert-ext id=dom-trees:concept-node-insert-ext-4 data-x-internal=concept-node-insert-ext>insertion steps</a> are invoked with it as the argument and it
  is now <a href=#browsing-context-connected id=dom-trees:browsing-context-connected>browsing-context connected</a>. A node <dfn id=becomes-browsing-context-disconnected data-lt="become browsing-context
  disconnected" data-export="">becomes browsing-context disconnected</dfn> either when the <a href=https://dom.spec.whatwg.org/#concept-node-remove-ext id=dom-trees:concept-node-remove-ext-4 data-x-internal=concept-node-remove-ext>removing steps</a> are invoked with it as the argument and it
  is now no longer <a href=#browsing-context-connected id=dom-trees:browsing-context-connected-2>browsing-context connected</a>, or when its <a id=dom-trees:shadow-including-root-2 href=https://dom.spec.whatwg.org/#concept-shadow-including-root data-x-internal=shadow-including-root>shadow-including
  root</a>'s <a href=document-sequences.html#concept-document-bc id=dom-trees:concept-document-bc-2>browsing context</a> becomes null.


  <h4 id=scripting-2><span class=secno>2.1.5</span> Scripting<a href=#scripting-2 class=self-link></a></h4>

  <p>The construction "a <code>Foo</code> object", where <code>Foo</code> is
  actually an interface, is sometimes used instead of the more accurate "an object implementing the
  interface <code>Foo</code>".</p>

  <p>An IDL attribute is said to be <dfn>getting</dfn> when its value is being retrieved
  (e.g. by author script), and is said to be <dfn>setting</dfn> when a new value is
  assigned to it.</p>

  <p>If a DOM object is said to be <dfn id=live>live</dfn>, then the attributes and methods on that object
  must operate on the actual underlying data, not a snapshot of the
  data.</p>


  <h4 id=plugins><span class=secno>2.1.6</span> Plugins<a href=#plugins class=self-link></a></h4>

  <p>The term <dfn id=plugin>plugin</dfn> refers to an <a id=plugins:implementation-defined href=https://infra.spec.whatwg.org/#implementation-defined data-x-internal=implementation-defined>implementation-defined</a> set of content
  handlers used by the user agent that can take part in the user agent's rendering of a
  <code id=plugins:document><a href=dom.html#document>Document</a></code> object, but that neither act as <a href=document-sequences.html#child-navigable id=plugins:child-navigable>child
  navigables</a> of the <code id=plugins:document-2><a href=dom.html#document>Document</a></code> nor introduce any <code id=plugins:node><a data-x-internal=node href=https://dom.spec.whatwg.org/#interface-node>Node</a></code> objects to the
  <code id=plugins:document-3><a href=dom.html#document>Document</a></code>'s DOM.</p>

  <p>Typically such content handlers are provided by third parties, though a user agent can also
  designate built-in content handlers as plugins.</p>

  

  <p>A user agent must not consider the types <code id=plugins:text/plain><a data-x-internal=text/plain href=https://www.rfc-editor.org/rfc/rfc2046#section-4.1.3>text/plain</a></code> and
  <code id=plugins:application/octet-stream><a data-x-internal=application/octet-stream href=https://www.rfc-editor.org/rfc/rfc2046#section-4.5.1>application/octet-stream</a></code> as having a registered <a href=#plugin id=plugins:plugin>plugin</a>.</p> 

  

  <p class=example>One example of a plugin would be a PDF viewer that is instantiated in a
  <a id=plugins:navigable href=document-sequences.html#navigable>navigable</a> when the user navigates to a PDF file. This would count as a plugin
  regardless of whether the party that implemented the PDF viewer component was the same as that
  which implemented the user agent itself. However, a PDF viewer application that launches separate
  from the user agent (as opposed to using the same interface) is not a plugin by this
  definition.</p>

  <p class=note>This specification does not define a mechanism for interacting with plugins, as it
  is expected to be user-agent- and platform-specific. Some UAs might opt to support a plugin
  mechanism such as the Netscape Plugin API; others might use remote content converters or have
  built-in support for certain types. Indeed, this specification doesn't require user agents to
  support plugins at all. <a href=references.html#refsNPAPI>[NPAPI]</a></p>

  

  <p class=warning>Browsers should take extreme care when interacting with external content
  intended for <a href=#plugin id=plugins:plugin-2>plugins</a>. When third-party software is run with the same
  privileges as the user agent itself, vulnerabilities in the third-party software become as
  dangerous as those in the user agent.</p>

  <p>
  <a id=plugins:tracking-vector title="There is a tracking vector here." href=https://infra.spec.whatwg.org/#tracking-vector class=tracking-vector data-x-internal=tracking-vector><img width=46 alt="(This is a tracking vector.)" crossorigin="" class=darkmode-aware src=https://resources.whatwg.org/tracking-vector.svg height=64></a>
  Since different users having different sets of <a href=#plugin id=plugins:plugin-3>plugins</a> provides a
  tracking vector that increases the chances of users being uniquely identified, user agents are
  encouraged to support the exact same set of <a href=#plugin id=plugins:plugin-4>plugins</a> for each
  user.</p>

  



  <h4 id=encoding-terminology><span class=secno>2.1.7</span> Character encodings<a href=#encoding-terminology class=self-link></a></h4>

  <p>A <dfn id=encoding><a href=https://encoding.spec.whatwg.org/#encoding>character
  encoding</a></dfn>, or just <i>encoding</i> where that is not ambiguous, is a defined way to convert
  between byte streams and Unicode strings, as defined in <cite>Encoding</cite>. An
  <a id=encoding-terminology:encoding href=https://encoding.spec.whatwg.org/#encoding data-x-internal=encoding>encoding</a> has an <dfn id=encoding-name><a href=https://encoding.spec.whatwg.org/#name>encoding
  name</a></dfn> and one or more <dfn id=encoding-label><a href=https://encoding.spec.whatwg.org/#label>encoding labels</a></dfn>, referred to as the
  encoding's <i>name</i> and <i>labels</i> in the Encoding standard. <a href=references.html#refsENCODING>[ENCODING]</a></p>



  

  <h4 id=conformance-classes><span class=secno>2.1.8</span> Conformance classes<a href=#conformance-classes class=self-link></a></h4>

  <p>This specification describes the conformance criteria for user agents
  (relevant to implementers) and documents (relevant to authors and
  authoring tool implementers).</p>

  <p><dfn id=conforming-documents>Conforming documents</dfn> are those that comply with all the conformance criteria for
  documents. For readability, some of these conformance requirements are phrased as conformance
  requirements on authors; such requirements are implicitly requirements on documents: by
  definition, all documents are assumed to have had an author. (In some cases, that author may
  itself be a user agent — such user agents are subject to additional rules, as explained
  below.)</p>

  <p class=example>For example, if a requirement states that "authors must not
  use the <code>foobar</code> element", it would imply that documents are not allowed to
  contain elements named <code>foobar</code>.</p>

  <p class="note impl">There is no implied relationship between document conformance requirements
  and implementation conformance requirements. User agents are not free to handle non-conformant
  documents as they please; the processing model described in this specification applies to
  implementations regardless of the conformity of the input documents.</p>

  <p>User agents fall into several (overlapping) categories with different conformance
  requirements.</p>

  <dl><dt id=interactive>Web browsers and other interactive user agents<dd>
    <p>Web browsers that support <a id=conformance-classes:the-xhtml-syntax href=xhtml.html#the-xhtml-syntax>the XML syntax</a> must process elements and attributes
    from the <a id=conformance-classes:html-namespace-2 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a> found in XML documents as described in this specification,
    so that users can interact with them, unless the semantics of those elements have been
    overridden by other specifications.</p>

    <p class=example>A conforming web browser would, upon finding a <code id=conformance-classes:the-script-element><a href=scripting.html#the-script-element>script</a></code> element in
    an XML document, execute the script contained in that element. However, if the element is found
    within a transformation expressed in XSLT (assuming the user agent also supports XSLT), then the
    processor would instead treat the <code id=conformance-classes:the-script-element-2><a href=scripting.html#the-script-element>script</a></code> element as an opaque element that forms
    part of the transform.</p>

    <p>Web browsers that support <a id=conformance-classes:syntax href=syntax.html#syntax>the HTML syntax</a> must process documents labeled with an
    <a id=conformance-classes:html-mime-type href=https://mimesniff.spec.whatwg.org/#html-mime-type data-x-internal=html-mime-type>HTML MIME type</a> as described in this specification, so that users can interact with
    them.</p>

    <p>User agents that support scripting must also be conforming implementations of the IDL
    fragments in this specification, as described in <cite>Web IDL</cite>. <a href=references.html#refsWEBIDL>[WEBIDL]</a></p>

    <p class=note>Unless explicitly stated, specifications that override the semantics of HTML
    elements do not override the requirements on DOM objects representing those elements. For
    example, the <code id=conformance-classes:the-script-element-3><a href=scripting.html#the-script-element>script</a></code> element in the example above would still implement the
    <code id=conformance-classes:htmlscriptelement><a href=scripting.html#htmlscriptelement>HTMLScriptElement</a></code> interface.</p>
   <dt id=non-interactive>Non-interactive presentation user agents<dd>
    <p>User agents that process HTML and XML documents purely to render non-interactive versions of
    them must comply to the same conformance criteria as web browsers, except that they are exempt
    from requirements regarding user interaction.</p>

    <p class=note>Typical examples of non-interactive presentation user agents are printers
    (static UAs) and overhead displays (dynamic UAs). It is expected that most static
    non-interactive presentation user agents will also opt to <a href=#non-scripted>lack scripting
    support</a>.</p>

    <p class=example>A non-interactive but dynamic presentation UA would still execute scripts,
    allowing forms to be dynamically submitted, and so forth. However, since the concept of "focus"
    is irrelevant when the user cannot interact with the document, the UA would not need to support
    any of the focus-related DOM APIs.</p>
   <dt id=renderingUA>Visual user agents that support the suggested default rendering<dd>
    <p>User agents, whether interactive or not, may be designated (possibly as a user option) as
    supporting the suggested default rendering defined by this specification.</p>

    <p>This is not required. In particular, even user agents that do implement the suggested default
    rendering are encouraged to offer settings that override this default to improve the experience
    for the user, e.g. changing the color contrast, using different focus styles, or otherwise
    making the experience more accessible and usable to the user.</p>

    <p>User agents that are designated as supporting the suggested default rendering must, while so
    designated, implement the rules <a href=rendering.html#rendering>the Rendering section</a> defines as the
    behavior that user agents are <em>expected</em> to implement.</p>
   <dt id=non-scripted>User agents with no scripting support<dd>
    <p>Implementations that do not support scripting (or which have their scripting features
    disabled entirely) are exempt from supporting the events and DOM interfaces mentioned in this
    specification. For the parts of this specification that are defined in terms of an events model
    or in terms of the DOM, such user agents must still act as if events and the DOM were
    supported.</p>

    <p class=note>Scripting can form an integral part of an application. Web browsers that do not
    support scripting, or that have scripting disabled, might be unable to fully convey the author's
    intent.</p>
   <dt>Conformance checkers<dd id=conformance-checkers>

    <p>Conformance checkers must verify that a document conforms to the applicable conformance
    criteria described in this specification. Automated conformance checkers are exempt from
    detecting errors that require interpretation of the author's intent (for example, while a
    document is non-conforming if the content of a <code id=conformance-classes:the-blockquote-element><a href=grouping-content.html#the-blockquote-element>blockquote</a></code> element is not a quote,
    conformance checkers running without the input of human judgement do not have to check that
    <code id=conformance-classes:the-blockquote-element-2><a href=grouping-content.html#the-blockquote-element>blockquote</a></code> elements only contain quoted material).</p>

    <p>Conformance checkers must check that the input document conforms when parsed without a
    <a href=document-sequences.html#concept-document-bc id=conformance-classes:concept-document-bc>browsing context</a> (meaning that no scripts are run, and
    that the parser's <a id=conformance-classes:scripting-flag href=parsing.html#scripting-flag>scripting flag</a> is disabled), and should also check that the input
    document conforms when parsed with a <a href=document-sequences.html#concept-document-bc id=conformance-classes:concept-document-bc-2>browsing context</a>
    in which scripts execute, and that the scripts never cause non-conforming states to occur other
    than transiently during script execution itself. (This is only a "SHOULD" and not a "MUST"
    requirement because it has been proven to be impossible. <a href=references.html#refsCOMPUTABLE>[COMPUTABLE]</a>)</p>

    <p>The term "HTML validator" can be used to refer to a conformance checker that itself conforms
    to the applicable requirements of this specification.</p>

    <div class=note>

     <p>XML DTDs cannot express all the conformance requirements of this specification. Therefore, a
     validating XML processor and a DTD cannot constitute a conformance checker. Also, since neither
     of the two authoring formats defined in this specification are applications of SGML, a
     validating SGML system cannot constitute a conformance checker either.</p>

     <p>To put it another way, there are three types of conformance criteria:</p>

     <ol><li>Criteria that can be expressed in a DTD.<li>Criteria that cannot be expressed by a DTD, but can still be checked by a machine.<li>Criteria that can only be checked by a human.</ol>

     <p>A conformance checker must check for the first two. A simple DTD-based validator only checks
     for the first class of errors and is therefore not a conforming conformance checker according
     to this specification.</p>

    </div>
   <dt>Data mining tools<dd id=data-mining>

    <p>Applications and tools that process HTML and XML documents for reasons other than to either
    render the documents or check them for conformance should act in accordance with the semantics
    of the documents that they process.</p>

    <p class=example>A tool that generates <a href=sections.html#outline id=conformance-classes:outline>document outlines</a> but
    increases the nesting level for each paragraph and does not increase the nesting level for
    <a href=sections.html#concept-heading id=conformance-classes:concept-heading>headings</a> would not be conforming.</p>
   <dt id=editors>Authoring tools and markup generators<dd>
    <p>Authoring tools and markup generators must generate <a href=#conforming-documents id=conformance-classes:conforming-documents>conforming documents</a>.
    Conformance criteria that apply to authors also apply to authoring tools, where appropriate.</p>

    <p>Authoring tools are exempt from the strict requirements of using elements only for their
    specified purpose, but only to the extent that authoring tools are not yet able to determine
    author intent. However, authoring tools must not automatically misuse elements or encourage
    their users to do so.</p>

    <p class=example>For example, it is not conforming to use an <code id=conformance-classes:the-address-element><a href=sections.html#the-address-element>address</a></code> element for
    arbitrary contact information; that element can only be used for marking up contact information
    for its nearest <code id=conformance-classes:the-article-element><a href=sections.html#the-article-element>article</a></code> or <code id=conformance-classes:the-body-element><a href=sections.html#the-body-element>body</a></code> element ancestor. However, since an
    authoring tool is likely unable to determine the difference, an authoring tool is exempt from
    that requirement. This does not mean, though, that authoring tools can use <code id=conformance-classes:the-address-element-2><a href=sections.html#the-address-element>address</a></code>
    elements for any block of italics text (for instance); it just means that the authoring tool
    doesn't have to verify that when the user uses a tool for inserting contact information for an
    <code id=conformance-classes:the-article-element-2><a href=sections.html#the-article-element>article</a></code> element, that the user really is doing that and not inserting something
    else instead.</p>

    <p class=note>In terms of conformance checking, an editor has to output documents that conform
    to the same extent that a conformance checker will verify.</p>

    <p>When an authoring tool is used to edit a non-conforming document, it may preserve the
    conformance errors in sections of the document that were not edited during the editing session
    (i.e. an editing tool is allowed to round-trip erroneous content). However, an authoring tool
    must not claim that the output is conformant if errors have been so preserved.</p>

    <p>Authoring tools are expected to come in two broad varieties: tools that work from structure
    or semantic data, and tools that work on a What-You-See-Is-What-You-Get media-specific editing
    basis (WYSIWYG).</p>

    <p>The former is the preferred mechanism for tools that author HTML, since the structure in the
    source information can be used to make informed choices regarding which HTML elements and
    attributes are most appropriate.</p>

    <p>However, WYSIWYG tools are legitimate. WYSIWYG tools should use elements they know are
    appropriate, and should not use elements that they do not know to be appropriate. This might in
    certain extreme cases mean limiting the use of flow elements to just a few elements, like
    <code id=conformance-classes:the-div-element><a href=grouping-content.html#the-div-element>div</a></code>, <code id=conformance-classes:the-b-element><a href=text-level-semantics.html#the-b-element>b</a></code>, <code id=conformance-classes:the-i-element><a href=text-level-semantics.html#the-i-element>i</a></code>, and <code id=conformance-classes:the-span-element><a href=text-level-semantics.html#the-span-element>span</a></code> and making liberal use
    of the <code id=conformance-classes:attr-style><a href=dom.html#attr-style>style</a></code> attribute.</p>

    <p>All authoring tools, whether WYSIWYG or not, should make a best effort attempt at enabling
    users to create well-structured, semantically rich, media-independent content.</p>
   </dl>

  <p>For compatibility with existing content and prior specifications, this specification describes
  two authoring formats: one based on <a href=xhtml.html#the-xhtml-syntax id=conformance-classes:the-xhtml-syntax-2>XML</a>, and one using a <a href=syntax.html#writing>custom format</a> inspired by SGML (referred to as <a id=conformance-classes:syntax-2 href=syntax.html#syntax>the HTML syntax</a>).
  Implementations must support at least one of these two formats, although supporting both is
  encouraged.</p>

  <p>Some conformance requirements are phrased as requirements on elements, attributes, methods or
  objects. Such requirements fall into two categories: those describing content model restrictions,
  and those describing implementation behavior. Those in the former category are requirements on
  documents and authoring tools. Those in the second category are requirements on user agents.
  Similarly, some conformance requirements are phrased as requirements on authors; such requirements
  are to be interpreted as conformance requirements on the documents that authors produce. (In other
  words, this specification does not distinguish between conformance criteria on authors and
  conformance criteria on documents.)</p>

  


  <h4 id=dependencies><span class=secno>2.1.9</span> Dependencies<a href=#dependencies class=self-link></a></h4>

  
  <div data-noexport="">

  <p>This specification relies on several other underlying specifications.</p>

  <dl><dt>Infra<dd>
    <p>The following terms are defined in <cite>Infra</cite>: <a href=references.html#refsINFRA>[INFRA]</a></p>

    <ul class=brief><li>The general iteration terms <dfn id=while><a href=https://infra.spec.whatwg.org/#iteration-while>while</a></dfn>,
             <dfn id=continue><a href=https://infra.spec.whatwg.org/#iteration-continue>continue</a></dfn>, and
             <dfn id=break><a href=https://infra.spec.whatwg.org/#iteration-break>break</a></dfn>.<li><dfn id=assert><a href=https://infra.spec.whatwg.org/#assert>Assert</a></dfn><li><dfn id=implementation-defined><a href=https://infra.spec.whatwg.org/#implementation-defined>implementation-defined</a></dfn><li><dfn id=willful-violation><a href=https://infra.spec.whatwg.org/#willful-violation>willful violation</a></dfn><li id=fingerprint><span id=fingerprinting-vector></span>
     <a id=dependencies:tracking-vector title="There is a tracking vector here." href=https://infra.spec.whatwg.org/#tracking-vector class=tracking-vector data-x-internal=tracking-vector><img width=46 alt="(This is a tracking vector.)" crossorigin="" class=darkmode-aware src=https://resources.whatwg.org/tracking-vector.svg height=64></a>
     <dfn id=tracking-vector><a href=https://infra.spec.whatwg.org/#tracking-vector>tracking vector</a></dfn><li><dfn id=code-point><a href=https://infra.spec.whatwg.org/#code-point>code point</a></dfn> and its synonym
         <dfn id=character><a href=https://infra.spec.whatwg.org/#code-point>character</a></dfn><li><dfn id=surrogate><a href=https://infra.spec.whatwg.org/#surrogate>surrogate</a></dfn><li><dfn id=scalar-value><a href=https://infra.spec.whatwg.org/#scalar-value>scalar value</a></dfn><li><dfn id=tuple><a href=https://infra.spec.whatwg.org/#tuple>tuple</a></dfn><li><dfn id=noncharacter><a href=https://infra.spec.whatwg.org/#noncharacter>noncharacter</a></dfn><li><dfn id=string><a href=https://infra.spec.whatwg.org/#string>string</a></dfn>,
         <dfn id=code-unit><a href=https://infra.spec.whatwg.org/#code-unit>code unit</a></dfn>,
         <dfn id=code-unit-prefix><a href=https://infra.spec.whatwg.org/#code-unit-prefix>code unit prefix</a></dfn>,
         <dfn id=code-unit-less-than><a href=https://infra.spec.whatwg.org/#code-unit-less-than>code unit less than</a></dfn>,
         <dfn id=starts-with><a href=https://infra.spec.whatwg.org/#string-starts-with>starts with</a></dfn>,
         <dfn id=ends-with><a href=https://infra.spec.whatwg.org/#string-ends-with>ends with</a></dfn>,
         <dfn id=length><a href=https://infra.spec.whatwg.org/#string-length>length</a></dfn>, and
         <dfn id=code-point-length><a href=https://infra.spec.whatwg.org/#string-code-point-length>code point length</a></dfn><li id=case-sensitive>The string equality operations <dfn id=is><a href=https://infra.spec.whatwg.org/#string-is>is</a></dfn> and
         <dfn id=identical-to><a href=https://infra.spec.whatwg.org/#string-is>identical to</a></dfn><li><dfn id=scalar-value-string><a href=https://infra.spec.whatwg.org/#scalar-value-string>scalar value string</a></dfn><li><dfn id=convert><a href=https://infra.spec.whatwg.org/#javascript-string-convert>convert</a></dfn><li><dfn id=ascii-string><a href=https://infra.spec.whatwg.org/#ascii-string>ASCII string</a></dfn><li><dfn id=ascii-tab-or-newline><a href=https://infra.spec.whatwg.org/#ascii-tab-or-newline>ASCII tab or newline</a></dfn><li><dfn id=space-characters><a href=https://infra.spec.whatwg.org/#ascii-whitespace>ASCII whitespace</a></dfn><li><dfn id=control><a href=https://infra.spec.whatwg.org/#control>control</a></dfn><li><dfn id=ascii-digits><a href=https://infra.spec.whatwg.org/#ascii-digit>ASCII digit</a></dfn><li><dfn id=uppercase-ascii-hex-digits><a href=https://infra.spec.whatwg.org/#ascii-upper-hex-digit>ASCII upper hex digit</a></dfn><li><dfn id=lowercase-ascii-hex-digits><a href=https://infra.spec.whatwg.org/#ascii-lower-hex-digit>ASCII lower hex digit</a></dfn><li><dfn id=ascii-hex-digits><a href=https://infra.spec.whatwg.org/#ascii-hex-digit>ASCII hex digit</a></dfn><li><dfn id=uppercase-ascii-letters><a href=https://infra.spec.whatwg.org/#ascii-upper-alpha>ASCII upper alpha</a></dfn><li><dfn id=lowercase-ascii-letters><a href=https://infra.spec.whatwg.org/#ascii-lower-alpha>ASCII lower alpha</a></dfn><li><dfn id=ascii-letters><a href=https://infra.spec.whatwg.org/#ascii-alpha>ASCII alpha</a></dfn><li><dfn id=alphanumeric-ascii-characters><a href=https://infra.spec.whatwg.org/#ascii-alphanumeric>ASCII alphanumeric</a></dfn><li><dfn id=isomorphic-decode><a href=https://infra.spec.whatwg.org/#isomorphic-decode>isomorphic decode</a></dfn><li><dfn id=isomorphic-encode><a href=https://infra.spec.whatwg.org/#isomorphic-encode>isomorphic encode</a></dfn><li><dfn id=converted-to-ascii-lowercase><a href=https://infra.spec.whatwg.org/#ascii-lowercase>ASCII lowercase</a></dfn><li><dfn id=converted-to-ascii-uppercase><a href=https://infra.spec.whatwg.org/#ascii-uppercase>ASCII uppercase</a></dfn><li><dfn id=ascii-case-insensitive><a href=https://infra.spec.whatwg.org/#ascii-case-insensitive>ASCII case-insensitive</a></dfn><li><dfn id=strip-newlines><a href=https://infra.spec.whatwg.org/#strip-newlines>strip newlines</a></dfn><li><dfn id=normalize-newlines><a href=https://infra.spec.whatwg.org/#normalize-newlines>normalize newlines</a></dfn><li><dfn id=strip-leading-and-trailing-ascii-whitespace><a href=https://infra.spec.whatwg.org/#strip-leading-and-trailing-ascii-whitespace>strip leading and trailing ASCII whitespace</a></dfn><li><dfn id=strip-and-collapse-ascii-whitespace><a href=https://infra.spec.whatwg.org/#strip-and-collapse-ascii-whitespace>strip and collapse ASCII whitespace</a></dfn><li><dfn id=split-a-string-on-spaces><a href=https://infra.spec.whatwg.org/#split-on-ascii-whitespace>split a string on ASCII whitespace</a></dfn><li><dfn id=split-a-string-on-commas><a href=https://infra.spec.whatwg.org/#split-on-commas>split a string on commas</a></dfn><li><dfn id=collect-a-sequence-of-code-points><a href=https://infra.spec.whatwg.org/#collect-a-sequence-of-code-points>collect a sequence of code points</a></dfn> and its associated
         <dfn id=position-variable><a href=https://infra.spec.whatwg.org/#string-position-variable>position variable</a></dfn><li><dfn id=skip-ascii-whitespace><a href=https://infra.spec.whatwg.org/#skip-ascii-whitespace>skip ASCII whitespace</a></dfn><li>The <dfn id=ordered-map><a href=https://infra.spec.whatwg.org/#ordered-map>ordered map</a></dfn> data structure and the associated definitions for
             <dfn id=map-key><a href=https://infra.spec.whatwg.org/#map-key>key</a></dfn>,
             <dfn id=map-value><a href=https://infra.spec.whatwg.org/#map-value>value</a></dfn>,
             <dfn id=map-empty><a href=https://infra.spec.whatwg.org/#map-is-empty>empty</a></dfn>,
             <dfn id=map-entry><a href=https://infra.spec.whatwg.org/#map-entry>entry</a></dfn>,
             <dfn id=map-exists><a href=https://infra.spec.whatwg.org/#map-exists>exists</a></dfn>,
             <dfn id=map-get><a href=https://infra.spec.whatwg.org/#map-get>getting the value of an entry</a></dfn>,
             <dfn id=map-set><a href=https://infra.spec.whatwg.org/#map-set>setting the value of an entry</a></dfn>,
             <dfn id=map-remove><a href=https://infra.spec.whatwg.org/#map-remove>removing an entry</a></dfn>,
             <dfn id=map-clear><a href=https://infra.spec.whatwg.org/#map-clear>clear</a></dfn>,
             <dfn id=map-get-the-keys><a href=https://infra.spec.whatwg.org/#map-getting-the-keys>getting the keys</a></dfn>,
             <dfn id=map-get-the-values><a href=https://infra.spec.whatwg.org/#map-getting-the-values>getting the values</a></dfn>,
             <dfn id=map-sort-descending><a href=https://infra.spec.whatwg.org/#map-sort-in-descending-order>sorting in descending order</a></dfn>,
             <dfn id=map-size><a href=https://infra.spec.whatwg.org/#map-size>size</a></dfn>, and
             <dfn id=map-iterate><a href=https://infra.spec.whatwg.org/#map-iterate>iterate</a></dfn><li>The <dfn id=list><a href=https://infra.spec.whatwg.org/#list>list</a></dfn> data structure and the associated definitions for
             <dfn id=list-append><a href=https://infra.spec.whatwg.org/#list-append>append</a></dfn>,
             <dfn id=list-extend><a href=https://infra.spec.whatwg.org/#list-extend>extend</a></dfn>,
             <dfn id=list-prepend><a href=https://infra.spec.whatwg.org/#list-prepend>prepend</a></dfn>,
             <dfn id=list-replace><a href=https://infra.spec.whatwg.org/#list-replace>replace</a></dfn>,
             <dfn id=list-remove><a href=https://infra.spec.whatwg.org/#list-remove>remove</a></dfn>,
             <dfn id=list-empty><a href=https://infra.spec.whatwg.org/#list-empty>empty</a></dfn>,
             <dfn id=list-contains><a href=https://infra.spec.whatwg.org/#list-contain>contains</a></dfn>,
             <dfn id=list-size><a href=https://infra.spec.whatwg.org/#list-size>size</a></dfn>,
             <dfn id=indices><a href=https://infra.spec.whatwg.org/#list-get-the-indices>indices</a></dfn>,
             <dfn id=list-is-empty><a href=https://infra.spec.whatwg.org/#list-is-empty>is empty</a></dfn>,
             <dfn id=list-item><a href=https://infra.spec.whatwg.org/#list-item>item</a></dfn>,
             <dfn id=list-iterate><a href=https://infra.spec.whatwg.org/#list-iterate>iterate</a></dfn>, and
             <dfn id=list-clone><a href=https://infra.spec.whatwg.org/#list-clone>clone</a></dfn>
             <dfn id=list-sort><a href=https://infra.spec.whatwg.org/#list-sort-in-ascending-order>sort in ascending order</a></dfn>
             <dfn id=list-sort-descending><a href=https://infra.spec.whatwg.org/#list-sort-in-descending-order>sort in descending order</a></dfn><li>The <dfn id=stack><a href=https://infra.spec.whatwg.org/#stack>stack</a></dfn> data structure and the associated definitions for
             <dfn id=stack-push><a href=https://infra.spec.whatwg.org/#stack-push>push</a></dfn> and
             <dfn id=stack-pop><a href=https://infra.spec.whatwg.org/#stack-pop>pop</a></dfn><li>The <dfn id=queue><a href=https://infra.spec.whatwg.org/#queue>queue</a></dfn> data structure and the associated definitions for
             <dfn id=enqueue><a href=https://infra.spec.whatwg.org/#queue-enqueue>enqueue</a></dfn> and
             <dfn id=dequeue><a href=https://infra.spec.whatwg.org/#queue-dequeue>dequeue</a></dfn><li>The <dfn id=set><a href=https://infra.spec.whatwg.org/#ordered-set>ordered set</a></dfn> data structure and the associated definition for
             <dfn id=set-append><a href=https://infra.spec.whatwg.org/#set-append>append</a></dfn> and
             <dfn id=set-union><a href=https://infra.spec.whatwg.org/#set-union>union</a></dfn><li>The <dfn id=struct><a href=https://infra.spec.whatwg.org/#struct>struct</a></dfn> specification type and the associated definition for
             <dfn id=struct-item><a href=https://infra.spec.whatwg.org/#struct-item>item</a></dfn><li>The <dfn id=byte-sequence><a href=https://infra.spec.whatwg.org/#byte-sequence>byte sequence</a></dfn> data structure<li>The <dfn id=forgiving-base64-encode><a href=https://infra.spec.whatwg.org/#forgiving-base64-encode>forgiving-base64 encode</a></dfn> and
             <dfn id=forgiving-base64-decode><a href=https://infra.spec.whatwg.org/#forgiving-base64-decode>forgiving-base64 decode</a></dfn> algorithms<li><dfn id=exclusive-range><a href=https://infra.spec.whatwg.org/#the-exclusive-range>exclusive range</a></dfn><li><dfn id=parse-a-json-string-to-an-infra-value><a href=https://infra.spec.whatwg.org/#parse-a-json-string-to-an-infra-value>parse a JSON string to an Infra value</a></dfn><li><dfn id=html-namespace-2><a href=https://infra.spec.whatwg.org/#html-namespace>HTML namespace</a></dfn><li><dfn id=mathml-namespace><a href=https://infra.spec.whatwg.org/#mathml-namespace>MathML namespace</a></dfn><li><dfn id=svg-namespace><a href=https://infra.spec.whatwg.org/#svg-namespace>SVG namespace</a></dfn><li><dfn id=xlink-namespace><a href=https://infra.spec.whatwg.org/#xlink-namespace>XLink namespace</a></dfn><li><dfn id=xml-namespace><a href=https://infra.spec.whatwg.org/#xml-namespace>XML namespace</a></dfn><li><dfn id=xmlns-namespace><a href=https://infra.spec.whatwg.org/#xmlns-namespace>XMLNS namespace</a></dfn></ul>
   <dt>Unicode and Encoding<dd>
    <p>The Unicode character set is used to represent textual data, and <cite>Encoding</cite>
    defines requirements around <a href=https://encoding.spec.whatwg.org/#encoding id=dependencies:encoding data-x-internal=encoding>character encodings</a>.
    <a href=references.html#refsUNICODE>[UNICODE]</a></p>

    <p class=note>This specification <a href=#encoding-terminology>introduces terminology</a>
    based on the terms defined in those specifications, as described earlier.</p>

    <p>The following terms are used as defined in <cite>Encoding</cite>: <a href=references.html#refsENCODING>[ENCODING]</a></p>

    <ul class=brief><li><dfn id=getting-an-encoding><a href=https://encoding.spec.whatwg.org/#concept-encoding-get>Getting an
     encoding</a></dfn><li><dfn id=get-an-output-encoding><a href=https://encoding.spec.whatwg.org/#get-an-output-encoding>Get an output
     encoding</a></dfn><li>The generic <dfn id=decode><a href=https://encoding.spec.whatwg.org/#decode>decode</a></dfn>
     algorithm which takes a byte stream and an encoding and returns a character stream<li>The <dfn id=utf-8-decode><a href=https://encoding.spec.whatwg.org/#utf-8-decode>UTF-8 decode</a></dfn>
     algorithm which takes a byte stream and returns a character stream, additionally stripping one
     leading UTF-8 Byte Order Mark (BOM), if any<li>The <dfn id=utf-8-decode-without-bom><a href=https://encoding.spec.whatwg.org/#utf-8-decode-without-bom>UTF-8
     decode without BOM</a></dfn> algorithm which is identical to <a id=dependencies:utf-8-decode href=https://encoding.spec.whatwg.org/#utf-8-decode data-x-internal=utf-8-decode>UTF-8 decode</a> except that
     it does not strip one leading UTF-8 Byte Order Mark (BOM)<li>The <dfn id=encode><a href=https://encoding.spec.whatwg.org/#encode>encode</a></dfn> algorithm
     which takes a character stream and an encoding and returns a byte stream<li>The <dfn id=utf-8-encode><a href=https://encoding.spec.whatwg.org/#utf-8-encode>UTF-8 encode</a></dfn>
     algorithm which takes a character stream and returns a byte stream<li>The <dfn id=bom-sniff><a href=https://encoding.spec.whatwg.org/#bom-sniff>BOM sniff</a></dfn>
     algorithm which takes a byte stream and returns an encoding or null.</ul>
   <dt>XML and related specifications<dd>
    <p>Implementations that support <a id=dependencies:the-xhtml-syntax href=xhtml.html#the-xhtml-syntax>the XML syntax</a> for HTML must support some version
    of XML, as well as its corresponding namespaces specification, because that syntax uses an XML
    serialization with namespaces. <a href=references.html#refsXML>[XML]</a> <a href=references.html#refsXMLNS>[XMLNS]</a></p>

    <p>Data mining tools and other user agents that perform operations on content without running
    scripts, evaluating CSS or XPath expressions, or otherwise exposing the resulting DOM to
    arbitrary content, may "support namespaces" by just asserting that their DOM node analogues are
    in certain namespaces, without actually exposing the namespace strings.</p>

    <p class=note>In <a id=dependencies:syntax href=syntax.html#syntax>the HTML syntax</a>, namespace prefixes and namespace declarations
    do not have the same effect as in XML. For instance, the colon has no special meaning in HTML
    element names.</p>

    <hr>

    <p>The attribute with the name <dfn id=attr-xml-space><a href=https://www.w3.org/TR/xml/#sec-white-space><code>space</code></a></dfn> in the <a id=dependencies:xml-namespace href=https://infra.spec.whatwg.org/#xml-namespace data-x-internal=xml-namespace>XML namespace</a> is defined by
    <cite>Extensible Markup Language</cite> (<cite>XML</cite>). <a href=references.html#refsXML>[XML]</a></p>

    <p>The <dfn id=xml-name><a href=https://www.w3.org/TR/xml/#NT-Name><code>Name</code></a></dfn> production is defined in <cite>XML</cite>.
    <a href=references.html#refsXML>[XML]</a></p>

    <p>This specification also references the <dfn id=xml-stylesheet><a href=https://www.w3.org/TR/xml-stylesheet/#the-xml-stylesheet-processing-instruction><code>&lt;?xml-stylesheet?></code></a></dfn>
    processing instruction, defined in <cite>Associating Style Sheets with XML documents</cite>.
    <a href=references.html#refsXMLSSPI>[XMLSSPI]</a></p>

    <p>This specification also non-normatively mentions the <dfn id=xsltprocessor><code>XSLTProcessor</code></dfn>
    interface and its <dfn id=dom-xsltprocessor-transformtofragment><code>transformToFragment()</code></dfn> and <dfn id=dom-xsltprocessor-transformtodocument><code>transformToDocument()</code></dfn> methods.
    <a href=references.html#refsXSLTP>[XSLTP]</a></p>
   <dt>URLs<dd>
    <p>The following terms are defined in <cite>URL</cite>: <a href=references.html#refsURL>[URL]</a></p>

    <ul class=brief><li><dfn id=concept-host><a href=https://url.spec.whatwg.org/#concept-host>host</a></dfn><li><dfn id=public-suffix><a href=https://url.spec.whatwg.org/#host-public-suffix>public suffix</a></dfn><li><dfn id=concept-domain><a href=https://url.spec.whatwg.org/#concept-domain>domain</a></dfn><li><dfn id=ip-address><a href=https://url.spec.whatwg.org/#ip-address>IP address</a></dfn><li><dfn id=url><a href=https://url.spec.whatwg.org/#concept-url>URL</a></dfn><li><dfn id=concept-url-origin><a href=https://url.spec.whatwg.org/#concept-url-origin>Origin</a></dfn> of URLs<li><dfn id=absolute-url><a href=https://url.spec.whatwg.org/#syntax-url-absolute>Absolute URL</a></dfn><li><dfn id=relative-url><a href=https://url.spec.whatwg.org/#syntax-url-relative>Relative URL</a></dfn><li><dfn id=registrable-domain><a href=https://url.spec.whatwg.org/#host-registrable-domain>registrable domain</a></dfn><li>The <dfn id=url-parser><a href=https://url.spec.whatwg.org/#concept-url-parser>URL parser</a></dfn>
     <li>The <dfn id=basic-url-parser><a href=https://url.spec.whatwg.org/#concept-basic-url-parser>basic URL parser</a></dfn> and its
      <dfn id=basic-url-parser-url><a href=https://url.spec.whatwg.org/#basic-url-parser-url><var>url</var></a></dfn> and
      <dfn id=basic-url-parser-state-override><a href=https://url.spec.whatwg.org/#basic-url-parser-state-override><var>state override</var></a></dfn>
      arguments, as well as these parser states:
      <ul class=brief><li><dfn id=scheme-start-state><a href=https://url.spec.whatwg.org/#scheme-start-state>scheme start state</a></dfn><li><dfn id=host-state><a href=https://url.spec.whatwg.org/#host-state>host state</a></dfn><li><dfn id=hostname-state><a href=https://url.spec.whatwg.org/#hostname-state>hostname state</a></dfn><li><dfn id=port-state><a href=https://url.spec.whatwg.org/#port-state>port state</a></dfn><li><dfn id=path-start-state><a href=https://url.spec.whatwg.org/#path-start-state>path start state</a></dfn><li><dfn id=query-state><a href=https://url.spec.whatwg.org/#query-state>query state</a></dfn><li><dfn id=fragment-state><a href=https://url.spec.whatwg.org/#fragment-state>fragment state</a></dfn></ul>
     <li>
      <dfn id=url-record><a href=https://url.spec.whatwg.org/#concept-url>URL record</a></dfn>, as well as its
      individual components:
      <ul class=brief><li><dfn id=concept-url-scheme><a href=https://url.spec.whatwg.org/#concept-url-scheme>scheme</a></dfn><li><dfn id=concept-url-username><a href=https://url.spec.whatwg.org/#concept-url-username>username</a></dfn><li><dfn id=concept-url-password><a href=https://url.spec.whatwg.org/#concept-url-password>password</a></dfn><li><dfn id=concept-url-host><a href=https://url.spec.whatwg.org/#concept-url-host>host</a></dfn><li><dfn id=concept-url-port><a href=https://url.spec.whatwg.org/#concept-url-port>port</a></dfn><li><dfn id=concept-url-path><a href=https://url.spec.whatwg.org/#concept-url-path>path</a></dfn><li><dfn id=concept-url-query><a href=https://url.spec.whatwg.org/#concept-url-query>query</a></dfn><li><dfn id=concept-url-fragment><a href=https://url.spec.whatwg.org/#concept-url-fragment>fragment</a></dfn><li><dfn id=concept-url-blob-entry><a href=https://url.spec.whatwg.org/#concept-url-blob-entry>blob URL entry</a></dfn></ul>
     <li><dfn id=valid-url-string><a href=https://url.spec.whatwg.org/#valid-url-string>valid URL string</a></dfn><li>The <dfn id=cannot-have-a-username/password/port><a href=https://url.spec.whatwg.org/#cannot-have-a-username-password-port>cannot have a username/password/port</a></dfn> concept<li>The <dfn id=opaque-path><a href=https://url.spec.whatwg.org/#url-opaque-path>opaque path</a></dfn> concept<li><dfn id=concept-url-serializer><a href=https://url.spec.whatwg.org/#concept-url-serializer>URL serializer</a></dfn> and its
         <dfn id=url-serializer-exclude-fragment><a href=https://url.spec.whatwg.org/#url-serializer-exclude-fragment>exclude fragment</a></dfn> argument<li><dfn id=url-path-serializer><a href=https://url.spec.whatwg.org/#url-path-serializer>URL path serializer</a></dfn><li>The <dfn id=host-parser><a href=https://url.spec.whatwg.org/#concept-host-parser>host parser</a></dfn><li>The <dfn id=host-serializer><a href=https://url.spec.whatwg.org/#concept-host-serializer>host serializer</a></dfn><li><dfn id=host-equals><a href=https://url.spec.whatwg.org/#concept-host-equals>Host equals</a></dfn><li><dfn id=concept-url-equals><a href=https://url.spec.whatwg.org/#concept-url-equals>URL equals</a></dfn> and its
         <dfn id=url-equals-exclude-fragments><a href=https://url.spec.whatwg.org/#url-equals-exclude-fragments>exclude fragments</a></dfn> argument<li><dfn id=serialize-an-integer><a href=https://url.spec.whatwg.org/#serialize-an-integer>serialize an integer</a></dfn><li><dfn id=default-encode-set><a href=https://url.spec.whatwg.org/#default-encode-set>Default encode set</a></dfn><li><dfn id=component-percent-encode-set><a href=https://url.spec.whatwg.org/#component-percent-encode-set>component percent-encode set</a></dfn><li><dfn id=utf-8-percent-encode><a href=https://url.spec.whatwg.org/#string-utf-8-percent-encode>UTF-8 percent-encode</a></dfn><li><dfn id=percent-decode><a href=https://url.spec.whatwg.org/#string-percent-decode>percent-decode</a></dfn><li><dfn id=set-the-username><a href=https://url.spec.whatwg.org/#set-the-username>set the username</a></dfn><li><dfn id=set-the-password><a href=https://url.spec.whatwg.org/#set-the-password>set the password</a></dfn><li>The <dfn id=application/x-www-form-urlencoded><a href=https://url.spec.whatwg.org/#concept-urlencoded><code>application/x-www-form-urlencoded</code></a></dfn> format<li>The <dfn id=application/x-www-form-urlencoded-serializer><a href=https://url.spec.whatwg.org/#concept-urlencoded-serializer><code>application/x-www-form-urlencoded</code> serializer</a></dfn><li><dfn id=is-special><a href=https://url.spec.whatwg.org/#is-special>is special</a></dfn></ul>

    <p>A number of schemes and protocols are referenced by this specification also:</p>

    <ul class=brief><li>The <dfn id=about-protocol><a href=https://www.rfc-editor.org/rfc/rfc6694#section-2><code>about:</code></a></dfn> scheme
     <a href=references.html#refsABOUT>[ABOUT]</a><li>The <dfn id=blob-protocol><a href=https://w3c.github.io/FileAPI/#DefinitionOfScheme><code>blob:</code></a></dfn> scheme
     <a href=references.html#refsFILEAPI>[FILEAPI]</a><li>The <dfn id=data-protocol><a href=https://www.rfc-editor.org/rfc/rfc2397#section-2><code>data:</code></a></dfn> scheme
     <a href=references.html#refsRFC2397>[RFC2397]</a><li>The <dfn id=http-protocol><a href=https://httpwg.org/specs/rfc7230.html#http.uri><code>http:</code></a></dfn> scheme
     <a href=references.html#refsHTTP>[HTTP]</a><li>The <dfn id=https-protocol><a href=https://httpwg.org/specs/rfc7230.html#https.uri><code>https:</code></a></dfn> scheme
     <a href=references.html#refsHTTP>[HTTP]</a><li>The <dfn id=mailto-protocol><a href=https://www.rfc-editor.org/rfc/rfc6068#section-2><code>mailto:</code></a></dfn>
     scheme <a href=references.html#refsMAILTO>[MAILTO]</a><li>The <dfn id=sms-protocol><a href=https://www.rfc-editor.org/rfc/rfc5724#section-2><code>sms:</code></a></dfn> scheme
     <a href=references.html#refsSMS>[SMS]</a><li>The <dfn id=urn-protocol><a href=https://www.rfc-editor.org/rfc/rfc2141#section-2><code>urn:</code></a></dfn> scheme
     <a href=references.html#refsURN>[URN]</a></ul>

    <p><dfn id=media-fragment-syntax><a href=https://www.w3.org/TR/media-frags/#media-fragment-syntax>Media fragment
    syntax</a></dfn> is defined in <cite>Media Fragments URI</cite>. <a href=references.html#refsMEDIAFRAG>[MEDIAFRAG]</a></p>
   <dt>URL Pattern<dd>
    <p>The following terms are defined in <cite>URL Pattern</cite>: <a href=references.html#refsURLPATTERN>[URLPATTERN]</a></p>

    <ul class=brief><li><dfn id=url-pattern><a href=https://urlpattern.spec.whatwg.org/#url-pattern>URL pattern</a></dfn><li><dfn id=url-pattern-match><a href=https://urlpattern.spec.whatwg.org/#url-pattern-match>match</a></dfn><li><dfn id=build-a-url-pattern-from-an-infra-value><a href=https://urlpattern.spec.whatwg.org/#build-a-url-pattern-from-an-infra-value>build a URL pattern from an Infra value</a></dfn><li><dfn id=parse-a-url-pattern-constructor-string><a href=https://urlpattern.spec.whatwg.org/#parse-a-constructor-string>parse a URL pattern constructor string</a></dfn><li><dfn id=urlpatterninit><a href=https://urlpattern.spec.whatwg.org/#dictdef-urlpatterninit><code>URLPatternInit</code></a></dfn></ul>
   <dt>HTTP and related specifications<dd>
    <p>The following terms are defined in the HTTP specifications: <a href=references.html#refsHTTP>[HTTP]</a></p>

    <ul class=brief><li>`<dfn id=http-accept><a href=https://httpwg.org/specs/rfc7231.html#header.accept><code>Accept</code></a></dfn>` header<li>`<dfn id=http-accept-language><a href=https://httpwg.org/specs/rfc7231.html#header.accept-language><code>Accept-Language</code></a></dfn>` header<li>`<dfn id=http-cache-control><a href=https://httpwg.org/specs/rfc7234.html#header.cache-control><code>Cache-Control</code></a></dfn>` header<li>`<dfn id=http-content-disposition><a href=https://httpwg.org/specs/rfc6266.html><code>Content-Disposition</code></a></dfn>` header<li>`<dfn id=http-content-language><a href=https://httpwg.org/specs/rfc7231.html#header.content-language><code>Content-Language</code></a></dfn>` header<li>`<dfn id=http-content-range><a href=https://httpwg.org/specs/rfc7233.html#header.content-range><code>Content-Range</code></a></dfn>` header<li>`<dfn id=http-last-modified><a href=https://httpwg.org/specs/rfc7232.html#header.last-modified><code>Last-Modified</code></a></dfn>` header<li>`<dfn id=http-range><a href=https://httpwg.org/specs/rfc7233.html#header.range><code>Range</code></a></dfn>` header<li>`<dfn id=http-referer><a href=https://httpwg.org/specs/rfc7231.html#header.referer><code>Referer</code></a></dfn>` header</ul>

    <p>The following terms are defined in <cite>HTTP State Management Mechanism</cite>:
    <a href=references.html#refsCOOKIES>[COOKIES]</a></p>

    <ul class=brief><li><dfn id=cookie-string><a href=https://httpwg.org/specs/rfc6265.html#sane-cookie-syntax>cookie-string</a></dfn><li><dfn id=receives-a-set-cookie-string><a href=https://httpwg.org/specs/rfc6265.html#storage-model>receives a set-cookie-string</a></dfn><li>`<dfn id=http-cookie><a href=https://httpwg.org/specs/rfc6265.html#cookie><code>Cookie</code></a></dfn>` header</ul>

    <p>The following term is defined in <cite>Web Linking</cite>: <a href=references.html#refsWEBLINK>[WEBLINK]</a></p>

    <ul class=brief><li>`<dfn id=http-link><a href=https://httpwg.org/specs/rfc8288.html#header><code>Link</code></a></dfn>` header<li><dfn id=parsing-a-link-field-value><a href=https://httpwg.org/specs/rfc8288.html#parse-fv>Parsing a `<code>Link</code>` field value</a></dfn></ul>

    <p>The following terms are defined in <cite>Structured Field Values for HTTP</cite>:
    <a href=references.html#refsSTRUCTURED-FIELDS>[STRUCTURED-FIELDS]</a></p>

    <ul class=brief><li><dfn id=http-structured-header><a href=https://httpwg.org/specs/rfc8941.html>structured header</a></dfn><li><dfn id=http-structured-header-boolean><a href=https://httpwg.org/specs/rfc8941.html#boolean>boolean</a></dfn><li><dfn id=http-structured-header-list><a href=https://httpwg.org/specs/rfc8941.html#list>list</a></dfn><li><dfn id=http-structured-header-parameters><a href=https://httpwg.org/specs/rfc8941.html#param>parameters</a></dfn><li><dfn id=http-structured-header-string><a href=https://httpwg.org/specs/rfc8941.html#string>string</a></dfn><li><dfn id=http-structured-header-token><a href=https://httpwg.org/specs/rfc8941.html#token>token</a></dfn></ul>

    <p>The following terms are defined in <cite>MIME Sniffing</cite>: <a href=references.html#refsMIMESNIFF>[MIMESNIFF]</a></p>

    <ul class=brief><li><dfn id=mime-type><a href=https://mimesniff.spec.whatwg.org/#mime-type>MIME type</a></dfn><li><dfn id=mime-type-essence><a href=https://mimesniff.spec.whatwg.org/#mime-type-essence>MIME type essence</a></dfn><li><dfn id=valid-mime-type-string><a href=https://mimesniff.spec.whatwg.org/#valid-mime-type>valid MIME type string</a></dfn><li><dfn id=valid-mime-type-string-with-no-parameters><a href=https://mimesniff.spec.whatwg.org/#valid-mime-type-with-no-parameters>valid MIME type string with no parameters</a></dfn><li><dfn id=html-mime-type><a href=https://mimesniff.spec.whatwg.org/#html-mime-type>HTML MIME type</a></dfn><li><dfn id=javascript-mime-type><a href=https://mimesniff.spec.whatwg.org/#javascript-mime-type>JavaScript MIME type</a></dfn> and
         <dfn id=javascript-mime-type-essence-match><a href=https://mimesniff.spec.whatwg.org/#javascript-mime-type-essence-match>JavaScript MIME type essence match</a></dfn><li><dfn id=json-mime-type><a href=https://mimesniff.spec.whatwg.org/#json-mime-type>JSON MIME type</a></dfn><li><dfn id=xml-mime-type><a href=https://mimesniff.spec.whatwg.org/#xml-mime-type>XML MIME type</a></dfn><li><dfn id=image-mime-type><a href=https://mimesniff.spec.whatwg.org/#image-mime-type>image MIME type</a></dfn><li><dfn id=audio-or-video-mime-type><a href=https://mimesniff.spec.whatwg.org/#audio-or-video-mime-type>audio or video MIME type</a></dfn><li><dfn id=font-mime-type><a href=https://mimesniff.spec.whatwg.org/#font-mime-type>font MIME type</a></dfn><li><dfn id=parse-a-mime-type><a href=https://mimesniff.spec.whatwg.org/#parse-a-mime-type>parse a MIME type</a></dfn><li><dfn id=is-mime-type-supported-by-the-user-agent><a href=https://mimesniff.spec.whatwg.org/#supported-by-the-user-agent>is MIME type supported by the user agent?</a></dfn></ul>
   <dt>Fetch<dd>
    <p>The following terms are defined in <cite>Fetch</cite>: <a href=references.html#refsFETCH>[FETCH]</a></p>

    <ul class=brief><li><dfn id=header-abnf><a href=https://fetch.spec.whatwg.org/#abnf>ABNF</a></dfn><li><dfn id=about:blank><code>about:blank</code></dfn><li>`<dfn id=sec-purpose><a href=https://fetch.spec.whatwg.org/#sec-purpose-header><code>Sec-Purpose</code></a></dfn>`<li>An <dfn id=http(s)-scheme><a href=https://fetch.spec.whatwg.org/#http-scheme>HTTP(S) scheme</a></dfn><li>A URL which <dfn id=is-local><a href=https://fetch.spec.whatwg.org/#is-local>is local</a></dfn><li>A <dfn id=local-scheme><a href=https://fetch.spec.whatwg.org/#local-scheme>local scheme</a></dfn><li>A <dfn id=fetch-scheme><a href=https://fetch.spec.whatwg.org/#fetch-scheme>fetch scheme</a></dfn><li><dfn id=cors-protocol><a href=https://fetch.spec.whatwg.org/#http-cors-protocol>CORS protocol</a></dfn><li><dfn id=default-user-agent-value><a href=https://fetch.spec.whatwg.org/#default-user-agent-value>default `<code>User-Agent</code>` value</a></dfn><li><dfn id=extract-a-mime-type><a href=https://fetch.spec.whatwg.org/#concept-header-extract-mime-type>extract a MIME type</a></dfn><li><dfn id=legacy-extract-an-encoding><a href=https://fetch.spec.whatwg.org/#legacy-extract-an-encoding>legacy extract an encoding</a></dfn><li><dfn id=concept-fetch><a href=https://fetch.spec.whatwg.org/#concept-fetch>fetch</a></dfn><li><dfn id=fetch-controller><a href=https://fetch.spec.whatwg.org/#fetch-controller>fetch controller</a></dfn><li><dfn id=process-the-next-manual-redirect><a href=https://fetch.spec.whatwg.org/#fetch-controller-process-the-next-manual-redirect>process the next manual redirect</a></dfn><li><dfn id=ok-status><a href=https://fetch.spec.whatwg.org/#ok-status>ok status</a></dfn><li><dfn id=navigation-request><a href=https://fetch.spec.whatwg.org/#navigation-request>navigation request</a></dfn><li><dfn id=network-error><a href=https://fetch.spec.whatwg.org/#concept-network-error>network error</a></dfn><li><dfn id=aborted-network-error><a href=https://fetch.spec.whatwg.org/#concept-aborted-network-error>aborted network error</a></dfn><li>`<dfn id=http-origin><a href=https://fetch.spec.whatwg.org/#http-origin><code>Origin</code></a></dfn>` header<li>`<dfn id=cross-origin-resource-policy><a href=https://fetch.spec.whatwg.org/#http-cross-origin-resource-policy><code>Cross-Origin-Resource-Policy</code></a></dfn>` header<li><dfn id=getting-a-structured-field-value><a href=https://fetch.spec.whatwg.org/#concept-header-list-get-structured-header>getting a structured field value</a></dfn><li><dfn id=concept-header-list><a href=https://fetch.spec.whatwg.org/#concept-header-list>header list</a></dfn><li><dfn id=concept-header-list-set><a href=https://fetch.spec.whatwg.org/#concept-header-list-set>set</a></dfn><li><dfn id=concept-header-list-get-decode-split><a href=https://fetch.spec.whatwg.org/#concept-header-list-get-decode-split>get, decode, and split</a></dfn><li><dfn id=fetch-controller-abort><a href=https://fetch.spec.whatwg.org/#fetch-controller-abort>abort</a></dfn><li><dfn id=cross-origin-resource-policy-check><a href=https://fetch.spec.whatwg.org/#cross-origin-resource-policy-check>cross-origin resource policy check</a></dfn><li>the <dfn id=requestcredentials><a href=https://fetch.spec.whatwg.org/#requestcredentials><code>RequestCredentials</code></a></dfn> enumeration<li>the <dfn id=requestdestination><a href=https://fetch.spec.whatwg.org/#requestdestination><code>RequestDestination</code></a></dfn> enumeration<li>the <dfn id=fetch()><a href=https://fetch.spec.whatwg.org/#dom-global-fetch><code>fetch()</code></a></dfn> method<li><dfn id=report-timing><a href=https://fetch.spec.whatwg.org/#finalize-and-report-timing>report timing</a></dfn><li><dfn id=serialize-a-response-url-for-reporting><a href=https://fetch.spec.whatwg.org/#serialize-a-response-url-for-reporting>serialize a response URL for reporting</a></dfn><li><dfn id=body-safely-extract><a href=https://fetch.spec.whatwg.org/#bodyinit-safely-extract>safely extracting a body</a></dfn><li><dfn id=body-incrementally-read><a href=https://fetch.spec.whatwg.org/#body-incrementally-read>incrementally reading a body</a></dfn><li><dfn id=processresponseconsumebody><a href=https://fetch.spec.whatwg.org/#process-response-end-of-body>processResponseConsumeBody</a></dfn><li><dfn id=processresponseendofbody><a href=https://fetch.spec.whatwg.org/#fetch-processresponseendofbody>processResponseEndOfBody</a></dfn><li><dfn id=processresponse><a href=https://fetch.spec.whatwg.org/#process-response>processResponse</a></dfn><li><dfn id=useparallelqueue><a href=https://fetch.spec.whatwg.org/#fetch-useparallelqueue>useParallelQueue</a></dfn><li><dfn id=processearlyhintsresponse><a href=https://fetch.spec.whatwg.org/#fetch-processearlyhintsresponse>processEarlyHintsResponse</a></dfn><li><dfn id=connection-pool><a href=https://fetch.spec.whatwg.org/#concept-connection-pool>connection pool</a></dfn><li><dfn id=obtain-a-connection><a href=https://fetch.spec.whatwg.org/#concept-connection-obtain>obtain a connection</a></dfn><li><dfn id=determine-the-network-partition-key><a href=https://fetch.spec.whatwg.org/#determine-the-network-partition-key>determine the network partition key</a></dfn><li><dfn id=extract-full-timing-info><a href=https://fetch.spec.whatwg.org/#extract-full-timing-info>extract full timing info</a></dfn><li><dfn id=as-a-body><a href=https://fetch.spec.whatwg.org/#byte-sequence-as-a-body>as a body</a></dfn><li><dfn id=response-body-info><a href=https://fetch.spec.whatwg.org/#response-body-info>response body info</a></dfn><li><dfn id=resolve-an-origin><a href=https://fetch.spec.whatwg.org/#resolve-an-origin>resolve an origin</a></dfn><li><dfn id=credentials><a href=https://fetch.spec.whatwg.org/#credentials>credentials</a></dfn><li><dfn id=reserve-deferred-fetch-quota><a href=https://fetch.spec.whatwg.org/#reserve-deferred-fetch-quota>reserve deferred fetch quota</a></dfn><li><dfn id=potentially-free-deferred-fetch-quota><a href=https://fetch.spec.whatwg.org/#reserve-deferred-fetch-quota>potentially free deferred fetch quota</a></dfn><li>
      <dfn id=concept-response><a href=https://fetch.spec.whatwg.org/#concept-response>response</a></dfn> and its
      associated:
      <ul class=brief><li><dfn id=concept-response-type><a href=https://fetch.spec.whatwg.org/#concept-response-type>type</a></dfn><li><dfn id=concept-response-url><a href=https://fetch.spec.whatwg.org/#concept-response-url>URL</a></dfn><li><dfn id=concept-response-url-list><a href=https://fetch.spec.whatwg.org/#concept-response-url-list>URL list</a></dfn><li><dfn id=concept-response-status><a href=https://fetch.spec.whatwg.org/#concept-response-status>status</a></dfn><li><dfn id=concept-response-header-list><a href=https://fetch.spec.whatwg.org/#concept-response-header-list>header list</a></dfn><li><dfn id=concept-response-body><a href=https://fetch.spec.whatwg.org/#concept-response-body>body</a></dfn><li><dfn id=concept-response-body-info><a href=https://fetch.spec.whatwg.org/#concept-response-body-info>body info</a></dfn><li><dfn id=concept-internal-response><a href=https://fetch.spec.whatwg.org/#concept-internal-response>internal response</a></dfn><li><dfn id=concept-response-location-url><a href=https://fetch.spec.whatwg.org/#concept-response-location-url>location URL</a></dfn><li><dfn id=concept-response-timing-info><a href=https://fetch.spec.whatwg.org/#concept-response-timing-info>timing info</a></dfn><li><dfn id=concept-response-service-worker-timing-info><a href=https://fetch.spec.whatwg.org/#response-service-worker-timing-info>service worker timing info</a></dfn><li><dfn id=concept-response-has-cross-origin-redirects><a href=https://fetch.spec.whatwg.org/#response-has-cross-origin-redirects>has-cross-origin-redirects</a></dfn><li><dfn id=concept-response-timing-allow-passed><a href=https://fetch.spec.whatwg.org/#concept-response-timing-allow-passed>timing allow passed</a></dfn><li>
        <dfn id=extract-content-range-values><a href=https://wicg.github.io/background-fetch/#extract-content-range-values>extract content-range values</a></dfn>
        
       </ul>
     <li>
      <dfn id=concept-request><a href=https://fetch.spec.whatwg.org/#concept-request>request</a></dfn> and its associated:
      <ul class=brief><li><dfn id=concept-request-url><a href=https://fetch.spec.whatwg.org/#concept-request-url>URL</a></dfn><li><dfn id=concept-request-method><a href=https://fetch.spec.whatwg.org/#concept-request-method>method</a></dfn><li><dfn id=concept-request-header-list><a href=https://fetch.spec.whatwg.org/#concept-request-header-list>header list</a></dfn><li><dfn id=concept-request-body><a href=https://fetch.spec.whatwg.org/#concept-request-body>body</a></dfn><li><dfn id=concept-request-client><a href=https://fetch.spec.whatwg.org/#concept-request-client>client</a></dfn><li><dfn id=concept-request-url-list><a href=https://fetch.spec.whatwg.org/#concept-request-url-list>URL list</a></dfn><li><dfn id=concept-request-current-url><a href=https://fetch.spec.whatwg.org/#concept-request-current-url>current URL</a></dfn><li><dfn id=concept-request-reserved-client><a href=https://fetch.spec.whatwg.org/#concept-request-reserved-client>reserved client</a></dfn><li><dfn id=concept-request-replaces-client-id><a href=https://fetch.spec.whatwg.org/#concept-request-replaces-client-id>replaces client id</a></dfn><li><dfn id=concept-request-initiator><a href=https://fetch.spec.whatwg.org/#concept-request-initiator>initiator</a></dfn><li><dfn id=concept-request-destination><a href=https://fetch.spec.whatwg.org/#concept-request-destination>destination</a></dfn><li><dfn id=concept-potential-destination><a href=https://fetch.spec.whatwg.org/#concept-potential-destination>potential destination</a></dfn><li><dfn id=concept-potential-destination-translate><a href=https://fetch.spec.whatwg.org/#concept-potential-destination-translate>translating</a></dfn> a <a href=https://fetch.spec.whatwg.org/#concept-potential-destination id=dependencies:concept-potential-destination data-x-internal=concept-potential-destination>potential destination</a><li><dfn id=concept-script-like-destination><a href=https://fetch.spec.whatwg.org/#request-destination-script-like>script-like</a></dfn> <a href=https://fetch.spec.whatwg.org/#concept-request-destination id=dependencies:concept-request-destination data-x-internal=concept-request-destination>destinations</a><li><dfn id=concept-request-priority><a href=https://fetch.spec.whatwg.org/#request-priority>priority</a></dfn><li><dfn id=concept-request-origin><a href=https://fetch.spec.whatwg.org/#concept-request-origin>origin</a></dfn><li><dfn id=concept-request-referrer><a href=https://fetch.spec.whatwg.org/#concept-request-referrer>referrer</a></dfn><li><dfn id=synchronous-flag><a href=https://fetch.spec.whatwg.org/#synchronous-flag>synchronous flag</a></dfn><li><dfn id=concept-request-mode><a href=https://fetch.spec.whatwg.org/#concept-request-mode>mode</a></dfn><li><dfn id=concept-request-credentials-mode><a href=https://fetch.spec.whatwg.org/#concept-request-credentials-mode>credentials mode</a></dfn><li><dfn id=use-url-credentials-flag><a href=https://fetch.spec.whatwg.org/#concept-request-use-url-credentials-flag>use-URL-credentials flag</a></dfn><li><dfn id=unsafe-request-flag><a href=https://fetch.spec.whatwg.org/#unsafe-request-flag>unsafe-request flag</a></dfn><li><dfn id=concept-request-cache-mode><a href=https://fetch.spec.whatwg.org/#concept-request-cache-mode>cache mode</a></dfn><li><dfn id=concept-request-redirect-count><a href=https://fetch.spec.whatwg.org/#concept-request-redirect-count>redirect count</a></dfn><li><dfn id=concept-request-redirect-mode><a href=https://fetch.spec.whatwg.org/#concept-request-redirect-mode>redirect mode</a></dfn><li><dfn id=concept-request-policy-container><a href=https://fetch.spec.whatwg.org/#concept-request-policy-container>policy container</a></dfn><li><dfn id=concept-request-referrer-policy><a href=https://fetch.spec.whatwg.org/#concept-request-referrer-policy>referrer policy</a></dfn><li><dfn id=concept-request-nonce-metadata><a href=https://fetch.spec.whatwg.org/#concept-request-nonce-metadata>cryptographic nonce metadata</a></dfn><li><dfn id=concept-request-integrity-metadata><a href=https://fetch.spec.whatwg.org/#concept-request-integrity-metadata>integrity metadata</a></dfn><li><dfn id=concept-request-parser-metadata><a href=https://fetch.spec.whatwg.org/#concept-request-parser-metadata>parser metadata</a></dfn><li><dfn id=concept-request-reload-navigation-flag><a href=https://fetch.spec.whatwg.org/#concept-request-reload-navigation-flag>reload-navigation flag</a></dfn><li><dfn id=concept-request-history-navigation-flag><a href=https://fetch.spec.whatwg.org/#concept-request-history-navigation-flag>history-navigation flag</a></dfn><li><dfn id=concept-request-user-activation><a href=https://fetch.spec.whatwg.org/#request-user-activation>user-activation</a></dfn><li><dfn id=concept-request-render-blocking><a href=https://fetch.spec.whatwg.org/#request-render-blocking>render-blocking</a></dfn><li><dfn id=concept-request-initiator-type><a href=https://fetch.spec.whatwg.org/#request-initiator-type>initiator type</a></dfn><li><dfn id=concept-request-service-workers-mode><a href=https://fetch.spec.whatwg.org/#request-service-workers-mode>service-workers mode</a></dfn><li><dfn id=concept-request-traversable-for-user-prompts><a href=https://fetch.spec.whatwg.org/#concept-request-window>traversable for user prompts</a></dfn><li><dfn id=top-level-navigation-initiator-origin><a href=https://fetch.spec.whatwg.org/#request-top-level-navigation-initiator-origin>top-level navigation initiator origin</a></dfn><li><dfn id=add-a-range-header><a href=https://fetch.spec.whatwg.org/#concept-request-add-range-header>add a range header</a></dfn></ul>
     <li>
      <dfn id=fetch-timing-info><a href=https://fetch.spec.whatwg.org/#fetch-timing-info>fetch timing info</a></dfn> and its
      associated:
      <ul class=brief><li><dfn id=fetch-timing-info-start-time><a href=https://fetch.spec.whatwg.org/#fetch-timing-info-start-time>start time</a></dfn><li><dfn id=fetch-timing-info-end-time><a href=https://fetch.spec.whatwg.org/#fetch-timing-info-end-time>end time</a></dfn></ul>
     </ul>

    <p>The following terms are defined in <cite>Referrer Policy</cite>:
    <a href=references.html#refsREFERRERPOLICY>[REFERRERPOLICY]</a></p>

    <ul class=brief><li><dfn id=referrer-policy><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy>referrer policy</a></dfn><li>The `<dfn id=http-referrer-policy><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-header-dfn><code>Referrer-Policy</code></a></dfn>` HTTP header<li>The <dfn id=parse-referrer-policy-header><a href=https://w3c.github.io/webappsec-referrer-policy/#parse-referrer-policy-from-header>parse a referrer policy from a `<code>Referrer-Policy</code>` header</a></dfn> algorithm<li>The "<dfn id=referrer-policy-no-referrer><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-no-referrer><code>no-referrer</code></a></dfn>",
             "<dfn id=referrer-policy-no-referrer-when-downgrade><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-no-referrer-when-downgrade><code>no-referrer-when-downgrade</code></a></dfn>",
             "<dfn id=referrer-policy-origin-when-cross-origin><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-origin-when-cross-origin><code>origin-when-cross-origin</code></a></dfn>", and
             "<dfn id=referrer-policy-unsafe-url><a href=https://w3c.github.io/webappsec-referrer-policy/#referrer-policy-unsafe-url><code>unsafe-url</code></a></dfn>" referrer policies<li>The <dfn id=default-referrer-policy><a href=https://w3c.github.io/webappsec-referrer-policy/#default-referrer-policy>default referrer policy</a></dfn></ul>

    <p>The following terms are defined in <cite>Mixed Content</cite>: <a href=references.html#refsMIX>[MIX]</a></p>

    <ul class=brief><li><dfn id=a-priori-authenticated-url><a href=https://w3c.github.io/webappsec-mixed-content/#a-priori-authenticated-url><i>a priori</i> authenticated URL</a></dfn></ul>

    <p>The following terms are defined in <cite>Subresource Integrity</cite>: <a href=references.html#refsSRI>[SRI]</a></p>

    <ul class=brief><li><dfn id=parse-integrity-metadata><a href=https://w3c.github.io/webappsec-subresource-integrity/#parse-metadata>parse integrity metadata</a></dfn><li><dfn id=the-requirements-of-the-integrity-attribute><a href=https://w3c.github.io/webappsec-subresource-integrity/#the-integrity-attribute>the requirements of the integrity attribute</a></dfn><li><dfn id=get-the-strongest-metadata-from-set><a href=https://w3c.github.io/webappsec-subresource-integrity/#get-the-strongest-metadata>get the strongest metadata from set</a></dfn><li><dfn id=integrity-policy><a href=https://w3c.github.io/webappsec-subresource-integrity/#integrity-policy>integrity policy</a></dfn><li><dfn id=parse-integrity-policy-headers><a href=https://w3c.github.io/webappsec-subresource-integrity/#parse-integrity-policy-headers>parse Integrity-Policy headers</a></dfn></ul>
   <dt>The No-Vary-Search HTTP Response Header Field<dd>
    <p>The following terms are defined in <cite>The No-Vary-Search HTTP Response Header
    Field</cite>: <a href=references.html#refsNOVARYSEARCH>[NOVARYSEARCH]</a></p>

    <ul class=brief><li>`<dfn id=no-vary-search><a href=https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#name-http-header-field-definitio><code>No-Vary-Search</code></a></dfn>`<li><dfn id=parse-a-url-search-variance><a href=https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#parse-a-url-search-variance>parse a URL search variance</a></dfn><li><dfn id=url-search-variance><a href=https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#name-data-model>URL search variance</a></dfn><li><dfn id=default-url-search-variance><a href=https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#name-data-model>default URL search variance</a></dfn><li><dfn id=equivalent-modulo-search-variance><a href=https://httpwg.org/http-extensions/draft-ietf-httpbis-no-vary-search.html#name-comparing>equivalent modulo search variance</a></dfn></ul>
   <dt>Paint Timing<dd>
    <p>The following terms are defined in <cite>Paint Timing</cite>: <a href=references.html#refsPAINTTIMING>[PAINTTIMING]</a></p>

    <ul class=brief><li><dfn id=mark-paint-timing><a href=https://w3c.github.io/paint-timing/#mark-paint-timing>mark paint timing</a></dfn></ul>
   <dt>Navigation Timing<dd>
    <p>The following terms are defined in <cite>Navigation Timing</cite>:
    <a href=references.html#refsNAVIGATIONTIMING>[NAVIGATIONTIMING]</a></p>

    <ul class=brief><li><dfn id=create-the-navigation-timing-entry><a href=https://w3c.github.io/navigation-timing/#dfn-create-the-navigation-timing-entry>create the navigation timing entry</a></dfn><li><dfn id=queue-the-navigation-timing-entry><a href=https://w3c.github.io/navigation-timing/#dfn-queue-the-navigation-timing-entry>queue the navigation timing entry</a></dfn><li><dfn id=navigationtimingtype><a href=https://w3c.github.io/navigation-timing/#dom-navigationtimingtype><code>NavigationTimingType</code></a></dfn> and its
         "<dfn id=dom-navigationtimingtype-navigate><a href=https://w3c.github.io/navigation-timing/#dom-navigationtimingtype-navigate><code>navigate</code></a></dfn>",
         "<dfn id=dom-navigationtimingtype-reload><a href=https://w3c.github.io/navigation-timing/#dom-navigationtimingtype-reload><code>reload</code></a></dfn>", and
         "<dfn id=dom-navigationtimingtype-back_forward><a href=https://w3c.github.io/navigation-timing/#dom-navigationtimingtype-back_forward><code>back_forward</code></a></dfn>" values.</ul>
   <dt>Resource Timing<dd>
    <p>The following terms are defined in <cite>Resource Timing</cite>:
    <a href=references.html#refsRESOURCETIMING>[RESOURCETIMING]</a></p>

    <ul class=brief><li><dfn id=mark-resource-timing><a href=https://w3c.github.io/resource-timing/#dfn-mark-resource-timing>Mark resource timing</a></dfn></ul>

   <dt>Performance Timeline<dd>
    <p>The following terms are defined in <cite>Performance Timeline</cite>:
    <a href=references.html#refsPERFORMANCETIMELINE>[PERFORMANCETIMELINE]</a></p>

    <ul class=brief><li><dfn id=performanceentry><a href=https://w3c.github.io/performance-timeline/#dom-performanceentry><code>PerformanceEntry</code></a></dfn> and its
         <dfn id=performanceentry-name><a href=https://w3c.github.io/performance-timeline/#dom-performanceentry-name><code>name</code></a></dfn>,
         <dfn id=performanceentry-entrytype><a href=https://w3c.github.io/performance-timeline/#dom-performanceentry-entrytype><code>entryType</code></a></dfn>,
         <dfn id=performanceentry-starttime><a href=https://w3c.github.io/performance-timeline/#dom-performanceentry-starttime><code>startTime</code></a></dfn>, and
         <dfn id=performanceentry-duration><a href=https://w3c.github.io/performance-timeline/#dom-performanceentry-duration><code>duration</code></a></dfn> attributes.<li><dfn id=queue-a-performance-entry><a href=https://w3c.github.io/performance-timeline/#queue-a-performanceentry>Queue a performance entry</a></dfn></ul>
   <dt>Long Animation Frames<dd>
    <p>The following terms are defined in <cite>Long Animation Frames</cite>: <a href=references.html#refsLONGANIMATIONFRAMES>[LONGANIMATIONFRAMES]</a></p>

    <ul class=brief><li><dfn id=record-task-start-time><a href=https://w3c.github.io/long-animation-frames/#record-task-start-time>record task start time</a></dfn><li><dfn id=record-task-end-time><a href=https://w3c.github.io/long-animation-frames/#record-task-end-time>record task end time</a></dfn><li><dfn id=record-rendering-time><a href=https://w3c.github.io/long-animation-frames/#record-rendering-time>record rendering time</a></dfn><li><dfn id=record-classic-script-creation-time><a href=https://w3c.github.io/long-animation-frames/#record-classic-script-creation-time>record classic script creation time</a></dfn><li><dfn id=record-classic-script-execution-start-time><a href=https://w3c.github.io/long-animation-frames/#record-classic-script-execution-start-time>record classic script execution start time</a></dfn><li><dfn id=record-module-script-execution-start-time><a href=https://w3c.github.io/long-animation-frames/#record-module-script-execution-start-time>record module script execution start time</a></dfn><li><dfn id=record-pause-duration><a href=https://w3c.github.io/long-animation-frames/#record-pause-duration>Record pause duration</a></dfn><li><dfn id=record-timing-info-for-timer-handler><a href=https://w3c.github.io/long-animation-frames/#record-timing-info-for-timer-handler>record timing info for timer handler</a></dfn><li><dfn id=record-timing-info-for-microtask-checkpoint><a href=https://w3c.github.io/long-animation-frames/#record-timing-info-for-microtask-checkpoint>record timing info for microtask checkpoint</a></dfn></ul>
   <dt>Long Tasks<dd>
    <p>The following terms are defined in <cite>Long Tasks</cite>: <a href=references.html#refsLONGTASKS>[LONGTASKS]</a></p>

    <ul class=brief><li><dfn id=report-long-tasks><a href=https://w3c.github.io/longtasks/#report-long-tasks>report long tasks</a></dfn></ul>
   <dt>Web IDL<dd>
    <p>The IDL fragments in this specification must be interpreted as required for conforming IDL
    fragments, as described in <cite>Web IDL</cite>. <a href=references.html#refsWEBIDL>[WEBIDL]</a></p>

    <p>The following terms are defined in <cite>Web IDL</cite>:</p>

    <ul class=brief><li><dfn id=this><a href=https://webidl.spec.whatwg.org/#this>this</a></dfn><li><dfn id=extended-attribute><a href=https://webidl.spec.whatwg.org/#dfn-extended-attribute>extended attribute</a></dfn><li><dfn id=named-constructor><a href=https://webidl.spec.whatwg.org/#dfn-named-constructor>named constructor</a></dfn><li><dfn id=constructor-operation><a href=https://webidl.spec.whatwg.org/#idl-constructors>constructor operation</a></dfn><li><dfn id=overridden-constructor-steps><a href=https://webidl.spec.whatwg.org/#overridden-constructor-steps>overridden constructor steps</a></dfn><li><dfn id=internally-create-a-new-object-implementing-the-interface><a href=https://webidl.spec.whatwg.org/#internally-create-a-new-object-implementing-the-interface>internally create a new object implementing the interface</a></dfn><li><dfn id=array-index-property-name><a href=https://webidl.spec.whatwg.org/#dfn-array-index-property-name>array index property name</a></dfn><li><dfn id=buffer-source-byte-length><a href=https://webidl.spec.whatwg.org/#buffersource-byte-length>buffer source byte length</a></dfn><li><dfn id=supports-indexed-properties><a href=https://webidl.spec.whatwg.org/#dfn-support-indexed-properties>supports indexed properties</a></dfn><li><dfn id=supported-property-indices><a href=https://webidl.spec.whatwg.org/#dfn-supported-property-indices>supported property indices</a></dfn><li><dfn id=determine-the-value-of-an-indexed-property><a href=https://webidl.spec.whatwg.org/#dfn-determine-the-value-of-an-indexed-property>determine the value of an indexed property</a></dfn><li><dfn id=set-the-value-of-an-existing-indexed-property><a href=https://webidl.spec.whatwg.org/#dfn-set-the-value-of-an-existing-indexed-property>set the value of an existing indexed property</a></dfn><li><dfn id=set-the-value-of-a-new-indexed-property><a href=https://webidl.spec.whatwg.org/#dfn-set-the-value-of-a-new-indexed-property>set the value of a new indexed property</a></dfn><li><dfn id=support-named-properties><a href=https://webidl.spec.whatwg.org/#dfn-support-named-properties>support named properties</a></dfn><li><dfn id=supported-property-names><a href=https://webidl.spec.whatwg.org/#dfn-supported-property-names>supported property names</a></dfn><li><dfn id=determine-the-value-of-a-named-property><a href=https://webidl.spec.whatwg.org/#dfn-determine-the-value-of-a-named-property>determine the value of a named property</a></dfn><li><dfn id=set-the-value-of-an-existing-named-property><a href=https://webidl.spec.whatwg.org/#dfn-set-the-value-of-an-existing-named-property>set the value of an existing named property</a></dfn><li><dfn id=set-the-value-of-a-new-named-property><a href=https://webidl.spec.whatwg.org/#dfn-set-the-value-of-a-new-named-property>set the value of a new named property</a></dfn><li><dfn id=delete-an-existing-named-property><a href=https://webidl.spec.whatwg.org/#dfn-delete-an-existing-named-property>delete an existing named property</a></dfn><li><dfn id=perform-a-security-check><a href=https://webidl.spec.whatwg.org/#dfn-perform-a-security-check>perform a security check</a></dfn><li><dfn id=platform-object><a href=https://webidl.spec.whatwg.org/#dfn-platform-object>platform object</a></dfn><li><dfn id=legacy-platform-object><a href=https://webidl.spec.whatwg.org/#dfn-legacy-platform-object>legacy platform object</a></dfn><li><dfn id=primary-interface><a href=https://webidl.spec.whatwg.org/#dfn-primary-interface>primary interface</a></dfn><li><dfn id=interface-object><a href=https://webidl.spec.whatwg.org/#dfn-interface-object>interface object</a></dfn><li><dfn id=named-properties-object><a href=https://webidl.spec.whatwg.org/#dfn-named-properties-object>named properties object</a></dfn><li><dfn id=include><a href=https://webidl.spec.whatwg.org/#include>include</a></dfn><li><dfn id=inherit><a href=https://webidl.spec.whatwg.org/#dfn-inherit>inherit</a></dfn><li><dfn id=interface-prototype-object><a href=https://webidl.spec.whatwg.org/#dfn-interface-prototype-object>interface prototype object</a></dfn><li><dfn id=implements><a href=https://webidl.spec.whatwg.org/#implements>implements</a></dfn><li><dfn id=associated-realm><a href=https://webidl.spec.whatwg.org/#dfn-associated-realm>associated realm</a></dfn><li><dfn id=realm-field-of-a-platform-object><a href=https://webidl.spec.whatwg.org/#es-platform-objects>[[Realm]] field of a platform object</a></dfn><li><dfn id=named-properties-object-getownproperty><a href=https://webidl.spec.whatwg.org/#named-properties-object-getownproperty>[[GetOwnProperty]] internal method of a named properties object</a></dfn><li><dfn id=callback-context><a href=https://webidl.spec.whatwg.org/#dfn-callback-context>callback context</a></dfn><li><dfn id=frozen-array><a href=https://webidl.spec.whatwg.org/#dfn-frozen-array-type>frozen array</a></dfn> and
         <dfn id=creating-a-frozen-array><a href=https://webidl.spec.whatwg.org/#dfn-create-frozen-array>creating a frozen array</a></dfn><li><dfn id=new><a href=https://webidl.spec.whatwg.org/#new>create a new object implementing the interface</a></dfn><li><dfn id=dfn-callback-this-value><a href=https://webidl.spec.whatwg.org/#dfn-callback-this-value>callback this value</a></dfn><li><dfn id=concept-idl-convert><a href=https://webidl.spec.whatwg.org/#es-type-mapping>converting</a></dfn> between Web IDL types and JS types<li><dfn id=es-invoking-callback-functions><a href=https://webidl.spec.whatwg.org/#invoke-a-callback-function>invoking</a></dfn> and
         <dfn id=es-constructing-callback-functions><a href=https://webidl.spec.whatwg.org/#construct-a-callback-function>constructing</a></dfn> callback functions<li><dfn id=overload-resolution-algorithm><a href=https://webidl.spec.whatwg.org/#dfn-overload-resolution-algorithm>overload resolution algorithm</a></dfn><li><dfn id=idl-exposed><a href=https://webidl.spec.whatwg.org/#dfn-exposed>exposed</a></dfn><li><dfn id=a-promise-resolved-with><a href=https://webidl.spec.whatwg.org/#a-promise-resolved-with>a promise resolved with</a></dfn><li><dfn id=a-promise-rejected-with><a href=https://webidl.spec.whatwg.org/#a-promise-rejected-with>a promise rejected with</a></dfn><li><dfn id=wait-for-all><a href=https://webidl.spec.whatwg.org/#wait-for-all>wait for all</a></dfn><li><dfn id=upon-rejection><a href=https://webidl.spec.whatwg.org/#upon-rejection>upon rejection</a></dfn><li><dfn id=upon-fulfillment><a href=https://webidl.spec.whatwg.org/#upon-fulfillment>upon fulfillment</a></dfn><li><dfn id=mark-as-handled><a href=https://webidl.spec.whatwg.org/#mark-a-promise-as-handled>mark as handled</a></dfn><li><dfn id=global><a href=https://webidl.spec.whatwg.org/#Global><code>[Global]</code></a></dfn><li><dfn id=legacyfactoryfunction><a href=https://webidl.spec.whatwg.org/#LegacyFactoryFunction><code>[LegacyFactoryFunction]</code></a></dfn><li><dfn id=legacylenientthis><a href=https://webidl.spec.whatwg.org/#LegacyLenientThis><code>[LegacyLenientThis]</code></a></dfn><li><dfn id=legacynulltoemptystring><a href=https://webidl.spec.whatwg.org/#LegacyNullToEmptyString><code>[LegacyNullToEmptyString]</code></a></dfn><li><dfn id=legacyoverridebuiltins><a href=https://webidl.spec.whatwg.org/#LegacyOverrideBuiltIns><code>[LegacyOverrideBuiltIns]</code></a></dfn><li><dfn id=legacyplatformobjectgetownproperty><a href=https://webidl.spec.whatwg.org/#LegacyPlatformObjectGetOwnProperty>LegacyPlatformObjectGetOwnProperty</a></dfn><li><dfn id=legacytreatnonobjectasnull><a href=https://webidl.spec.whatwg.org/#LegacyTreatNonObjectAsNull><code>[LegacyTreatNonObjectAsNull]</code></a></dfn><li><dfn id=legacyunenumerablenamedproperties><a href=https://webidl.spec.whatwg.org/#LegacyUnenumerableNamedProperties><code>[LegacyUnenumerableNamedProperties]</code></a></dfn><li><dfn id=legacyunforgeable><a href=https://webidl.spec.whatwg.org/#LegacyUnforgeable><code>[LegacyUnforgeable]</code></a></dfn><li><dfn id=set-entries><a href=https://webidl.spec.whatwg.org/#dfn-set-entries>set entries</a></dfn></ul>

    <p><cite>Web IDL</cite> also defines the following types that are used in Web IDL fragments in
    this specification:</p>

    <ul class=brief><li><dfn id=idl-arraybuffer><a href=https://webidl.spec.whatwg.org/#idl-ArrayBuffer><code>ArrayBuffer</code></a></dfn><li><dfn id=idl-arraybufferview><a href=https://webidl.spec.whatwg.org/#common-ArrayBufferView><code>ArrayBufferView</code></a></dfn><li><dfn id=idl-boolean><a href=https://webidl.spec.whatwg.org/#idl-boolean><code>boolean</code></a></dfn><li><dfn id=idl-domstring><a href=https://webidl.spec.whatwg.org/#idl-DOMString><code>DOMString</code></a></dfn><li><dfn id=idl-double><a href=https://webidl.spec.whatwg.org/#idl-double><code>double</code></a></dfn><li><dfn id=idl-enumeration><a href=https://webidl.spec.whatwg.org/#idl-enums>enumeration</a></dfn><li><dfn id=idl-float16array><a href=https://webidl.spec.whatwg.org/#idl-Float16Array><code>Float16Array</code></a></dfn><li><dfn id=idl-function><a href=https://webidl.spec.whatwg.org/#common-Function><code>Function</code></a></dfn><li><dfn id=idl-long><a href=https://webidl.spec.whatwg.org/#idl-long><code>long</code></a></dfn><li><dfn id=idl-object><a href=https://webidl.spec.whatwg.org/#idl-object><code>object</code></a></dfn><li><dfn id=idl-promise><a href=https://webidl.spec.whatwg.org/#idl-promise><code>Promise</code></a></dfn><li><dfn id=idl-uint8clampedarray><a href=https://webidl.spec.whatwg.org/#idl-Uint8ClampedArray><code>Uint8ClampedArray</code></a></dfn><li><dfn id=idl-unrestricted-double><a href=https://webidl.spec.whatwg.org/#idl-unrestricted-double><code>unrestricted double</code></a></dfn><li><dfn id=idl-unsigned-long><a href=https://webidl.spec.whatwg.org/#idl-unsigned-long><code>unsigned long</code></a></dfn><li><dfn id=idl-usvstring><a href=https://webidl.spec.whatwg.org/#idl-USVString><code>USVString</code></a></dfn><li><dfn id=idl-voidfunction><a href=https://webidl.spec.whatwg.org/#VoidFunction><code>VoidFunction</code></a></dfn></ul>

    <p>The term <dfn id=throw><a href=https://webidl.spec.whatwg.org/#dfn-throw>throw</a></dfn> in this
    specification is used as defined in <cite>Web IDL</cite>. The <dfn id=domexception><a href=https://webidl.spec.whatwg.org/#dfn-DOMException><code>DOMException</code></a></dfn>
    type and the following exception names are defined by Web IDL and used by this
    specification:</p>

    <ul class=brief><li><dfn id=indexsizeerror><a href=https://webidl.spec.whatwg.org/#indexsizeerror>"<code>IndexSizeError</code>"</a></dfn><li><dfn id=hierarchyrequesterror><a href=https://webidl.spec.whatwg.org/#hierarchyrequesterror>"<code>HierarchyRequestError</code>"</a></dfn><li><dfn id=invalidcharactererror><a href=https://webidl.spec.whatwg.org/#invalidcharactererror>"<code>InvalidCharacterError</code>"</a></dfn><li><dfn id=nomodificationallowederror><a href=https://webidl.spec.whatwg.org/#nomodificationallowederror>"<code>NoModificationAllowedError</code>"</a></dfn><li><dfn id=notfounderror><a href=https://webidl.spec.whatwg.org/#notfounderror>"<code>NotFoundError</code>"</a></dfn><li><dfn id=notsupportederror><a href=https://webidl.spec.whatwg.org/#notsupportederror>"<code>NotSupportedError</code>"</a></dfn><li><dfn id=invalidstateerror><a href=https://webidl.spec.whatwg.org/#invalidstateerror>"<code>InvalidStateError</code>"</a></dfn><li><dfn id=syntaxerror><a href=https://webidl.spec.whatwg.org/#syntaxerror>"<code>SyntaxError</code>"</a></dfn><li><dfn id=invalidaccesserror><a href=https://webidl.spec.whatwg.org/#invalidaccesserror>"<code>InvalidAccessError</code>"</a></dfn><li><dfn id=securityerror><a href=https://webidl.spec.whatwg.org/#securityerror>"<code>SecurityError</code>"</a></dfn><li><dfn id=networkerror><a href=https://webidl.spec.whatwg.org/#networkerror>"<code>NetworkError</code>"</a></dfn><li><dfn id=aborterror><a href=https://webidl.spec.whatwg.org/#aborterror>"<code>AbortError</code>"</a></dfn><li><dfn id=quotaexceedederror><a href=https://webidl.spec.whatwg.org/#quotaexceedederror>"<code>QuotaExceededError</code>"</a></dfn><li><dfn id=datacloneerror><a href=https://webidl.spec.whatwg.org/#datacloneerror>"<code>DataCloneError</code>"</a></dfn><li><dfn id=encodingerror><a href=https://webidl.spec.whatwg.org/#encodingerror>"<code>EncodingError</code>"</a></dfn><li><dfn id=notallowederror><a href=https://webidl.spec.whatwg.org/#notallowederror>"<code>NotAllowedError</code>"</a></dfn></ul>

    <p>When this specification requires a user agent to <dfn id=create-a-date-object>create a <code>Date</code> object</dfn>
    representing a particular time (which could be the special value Not-a-Number), the milliseconds
    component of that time, if any, must be truncated to an integer, and the time value of the newly
    created <code id=dependencies:date><a data-x-internal=date href=https://tc39.es/ecma262/#sec-date-objects>Date</a></code> object must represent the resulting truncated time.</p>

    <p class=example>For instance, given the time 23045 millionths of a second after 01:00 UTC on
    January 1st 2000, i.e. the time 2000-01-01T00:00:00.023045Z, then the <code id=dependencies:date-2><a data-x-internal=date href=https://tc39.es/ecma262/#sec-date-objects>Date</a></code> object
    created representing that time would represent the same time as that created representing the
    time 2000-01-01T00:00:00.023Z, 45 millionths earlier. If the given time is NaN, then the result
    is a <code id=dependencies:date-3><a data-x-internal=date href=https://tc39.es/ecma262/#sec-date-objects>Date</a></code> object that represents a time value NaN (indicating that the object does
    not represent a specific instant of time).</p>
   <dt>JavaScript<dd>
    <p>Some parts of the language described by this specification only support JavaScript as the
    underlying scripting language. <a href=references.html#refsJAVASCRIPT>[JAVASCRIPT]</a></p>

    <p class=note>The term "JavaScript" is used to refer to ECMA-262, rather than the official
    term ECMAScript, since the term JavaScript is more widely known.</p>

    <p>The following terms are defined in the JavaScript specification and used in this
    specification:</p>

    <ul class=brief><li><dfn id=active-function-object><a href=https://tc39.es/ecma262/#active-function-object>active function object</a></dfn><li><dfn id=agent><a href=https://tc39.es/ecma262/#sec-agents>agent</a></dfn> and
         <dfn id=agent-cluster><a href=https://tc39.es/ecma262/#sec-agent-clusters>agent cluster</a></dfn><li><dfn id=automatic-semicolon-insertion><a href=https://tc39.es/ecma262/#sec-automatic-semicolon-insertion>automatic semicolon insertion</a></dfn><li><dfn id=candidate-execution><a href=https://tc39.es/ecma262/#sec-candidate-executions>candidate execution</a></dfn><li>The <dfn id=current-realm><a href=https://tc39.es/ecma262/#current-realm>current realm</a></dfn><li><dfn id=clamping><a href=https://tc39.es/ecma262/#clamping>clamping</a></dfn> a mathematical value<li><dfn id=early-error><a href=https://tc39.es/ecma262/#early-error-rule>early error</a></dfn><li><dfn id=forward-progress><a href=https://tc39.es/ecma262/#sec-forward-progress>forward progress</a></dfn><li><dfn id=invariants-of-the-essential-internal-methods><a href=https://tc39.es/ecma262/#sec-invariants-of-the-essential-internal-methods>invariants of the essential internal methods</a></dfn><li><dfn id=javascript-execution-context><a href=https://tc39.es/ecma262/#sec-execution-contexts>JavaScript execution context</a></dfn><li><dfn id=javascript-execution-context-stack><a href=https://tc39.es/ecma262/#execution-context-stack>JavaScript execution context stack</a></dfn><li><dfn id=realm><a href=https://tc39.es/ecma262/#sec-code-realms>realm</a></dfn><li><dfn id=jobcallback-record><a href=https://tc39.es/ecma262/#sec-jobcallback-records>JobCallback Record</a></dfn><li><dfn id=newtarget><a href=https://tc39.es/ecma262/#sec-built-in-function-objects>NewTarget</a></dfn><li><dfn id=running-javascript-execution-context><a href=https://tc39.es/ecma262/#running-execution-context>running JavaScript execution context</a></dfn><li><dfn id=surrounding-agent><a href=https://tc39.es/ecma262/#surrounding-agent>surrounding agent</a></dfn><li><dfn id=abstract-closure><a href=https://tc39.es/ecma262/#sec-abstract-closure>abstract closure</a></dfn><li><dfn id=immutable-prototype-exotic-object><a href=https://tc39.es/ecma262/#immutable-prototype-exotic-object>immutable prototype exotic object</a></dfn><li><dfn id=well-known-symbols><a href=https://tc39.es/ecma262/#sec-well-known-symbols>Well-Known Symbols</a></dfn>, including
         <dfn id=symbol.hasinstance>%Symbol.hasInstance%</dfn>,
         <dfn id=symbol.isconcatspreadable>%Symbol.isConcatSpreadable%</dfn>,
         <dfn id=symbol.toprimitive>%Symbol.toPrimitive%</dfn>, and
         <dfn id=symbol.tostringtag>%Symbol.toStringTag%</dfn><li><dfn id=well-known-intrinsic-objects><a href=https://tc39.es/ecma262/#sec-well-known-intrinsic-objects>Well-Known Intrinsic Objects</a></dfn>, including
         <dfn id=array.prototype><a href=https://tc39.es/ecma262/#sec-properties-of-the-array-prototype-object>%Array.prototype%</a></dfn>,
         <dfn id=error.prototype><a href=https://tc39.es/ecma262/#sec-properties-of-the-error-prototype-object>%Error.prototype%</a></dfn>,
         <dfn id=evalerror.prototype>%EvalError.prototype%</dfn>,
         <dfn id=function.prototype><a href=https://tc39.es/ecma262/#sec-properties-of-the-function-prototype-object>%Function.prototype%</a></dfn>,
         <dfn id=object.prototype><a href=https://tc39.es/ecma262/#sec-properties-of-the-object-prototype-object>%Object.prototype%</a></dfn>,
         <dfn id=object.prototype.valueof><a href=https://tc39.es/ecma262/#sec-object.prototype.valueof>%Object.prototype.valueOf%</a></dfn>,
         <dfn id=rangeerror.prototype>%RangeError.prototype%</dfn>,
         <dfn id=referenceerror.prototype>%ReferenceError.prototype%</dfn>,
         <dfn id=syntaxerror.prototype>%SyntaxError.prototype%</dfn>,
         <dfn id=typeerror.prototype>%TypeError.prototype%</dfn>, and
         <dfn id=urierror.prototype>%URIError.prototype%</dfn><li>The <dfn id=js-prod-functionbody><a href=https://tc39.es/ecma262/#prod-FunctionBody><i>FunctionBody</i></a></dfn> production<li>The <dfn id=js-prod-module><a href=https://tc39.es/ecma262/#prod-Module><i>Module</i></a></dfn> production<li>The <dfn id=js-prod-pattern><a href=https://tc39.es/ecma262/#prod-Pattern><i>Pattern</i></a></dfn> production<li>The <dfn id=js-prod-script><a href=https://tc39.es/ecma262/#prod-Script><i>Script</i></a></dfn> production<li>The
     <dfn id=js-bigint><a href=https://tc39.es/ecma262/#sec-ecmascript-language-types-bigint-type>BigInt</a></dfn>,
     <dfn id=js-boolean><a href=https://tc39.es/ecma262/#sec-ecmascript-language-types-boolean-type>Boolean</a></dfn>,
     <dfn id=js-number><a href=https://tc39.es/ecma262/#sec-ecmascript-language-types-number-type>Number</a></dfn>,
     <dfn id=js-string><a href=https://tc39.es/ecma262/#sec-ecmascript-language-types-string-type>String</a></dfn>,
     <dfn id=js-symbol><a href=https://tc39.es/ecma262/#sec-ecmascript-language-types-symbol-type>Symbol</a></dfn>,
     and <dfn id=js-object><a href=https://tc39.es/ecma262/#sec-object-type>Object</a></dfn> ECMAScript language types<li>The <dfn id=completion-record><a href=https://tc39.es/ecma262/#sec-completion-record-specification-type>Completion Record</a></dfn> specification type<li>The <dfn id=js-list><a href=https://tc39.es/ecma262/#sec-list-and-record-specification-type>List</a></dfn> and
             <dfn id=record><a href=https://tc39.es/ecma262/#sec-list-and-record-specification-type>Record</a></dfn> specification types<li>The <dfn id=propertydescriptor><a href=https://tc39.es/ecma262/#sec-property-descriptor-specification-type>Property Descriptor</a></dfn> specification type<li>The <dfn id=modulerequest-record><a href=https://tc39.es/ecma262/#modulerequest-record>ModuleRequest Record</a></dfn> specification type<li>The <dfn id=script-record><a href=https://tc39.es/ecma262/#sec-script-records>Script Record</a></dfn> specification type<li>The <dfn id=synthetic-module-record><a href=https://tc39.es/ecma262/#sec-synthetic-module-records>Synthetic Module Record</a></dfn> specification type<li>The <dfn id=cyclic-module-record><a href=https://tc39.es/ecma262/#sec-cyclic-module-records>Cyclic Module Record</a></dfn> specification type<li>The <dfn id=source-text-module-record><a href=https://tc39.es/ecma262/#sec-source-text-module-records>Source Text Module Record</a></dfn> specification type and its
             <dfn id=js-evaluate><a href=https://tc39.es/ecma262/#sec-moduleevaluation>Evaluate</a></dfn>,
             <dfn id=js-link><a href=https://tc39.es/ecma262/#sec-moduledeclarationlinking>Link</a></dfn> and
             <dfn id=js-loadrequestedmodules><a href=https://tc39.es/ecma262/#sec-LoadRequestedModules>LoadRequestedModules</a></dfn> methods<li>The <dfn id=arraycreate><a href=https://tc39.es/ecma262/#sec-arraycreate>ArrayCreate</a></dfn> abstract operation<li>The <dfn id=call><a href=https://tc39.es/ecma262/#sec-call>Call</a></dfn> abstract operation<li>The <dfn id=clearkeptobjects><a href=https://tc39.es/ecma262/#sec-clear-kept-objects>ClearKeptObjects</a></dfn> abstract operation<li>The <dfn id=cleanupfinalizationregistry><a href=https://tc39.es/ecma262/#sec-cleanup-finalization-registry>CleanupFinalizationRegistry</a></dfn> abstract operation<li>The <dfn id=construct><a href=https://tc39.es/ecma262/#sec-construct>Construct</a></dfn> abstract operation<li>The <dfn id=copydatablockbytes><a href=https://tc39.es/ecma262/#sec-copydatablockbytes>CopyDataBlockBytes</a></dfn> abstract operation<li>The <dfn id=createbuiltinfunction><a href=https://tc39.es/ecma262/#sec-createbuiltinfunction>CreateBuiltinFunction</a></dfn> abstract operation<li>The <dfn id=createbytedatablock><a href=https://tc39.es/ecma262/#sec-createbytedatablock>CreateByteDataBlock</a></dfn> abstract operation<li>The <dfn id=createdataproperty><a href=https://tc39.es/ecma262/#sec-createdataproperty>CreateDataProperty</a></dfn> abstract operation<li>The <dfn id=createdefaultexportsyntheticmodule><a href=https://tc39.es/ecma262/#sec-create-default-export-synthetic-module>CreateDefaultExportSyntheticModule</a></dfn> abstract operation<li>The <dfn id=definepropertyorthrow><a href=https://tc39.es/ecma262/#sec-definepropertyorthrow>DefinePropertyOrThrow</a></dfn> abstract operation<li>The <dfn id=detacharraybuffer><a href=https://tc39.es/ecma262/#sec-detacharraybuffer>DetachArrayBuffer</a></dfn> abstract operation<li>The <dfn id=enumerableownproperties><a href=https://tc39.es/ecma262/#sec-enumerableownproperties>EnumerableOwnProperties</a></dfn> abstract operation<li>The <dfn id=finishloadingimportedmodule><a href=https://tc39.es/ecma262/#sec-FinishLoadingImportedModule>FinishLoadingImportedModule</a></dfn> abstract operation<li>The <dfn id=js-ordinaryfunctioncreate><a href=https://tc39.es/ecma262/#sec-ordinaryfunctioncreate>OrdinaryFunctionCreate</a></dfn> abstract operation<li>The <dfn id=js-get><a href=https://tc39.es/ecma262/#sec-get-o-p>Get</a></dfn> abstract operation<li>The <dfn id=getactivescriptormodule><a href=https://tc39.es/ecma262/#sec-getactivescriptormodule>GetActiveScriptOrModule</a></dfn> abstract operation<li>The <dfn id=getfunctionrealm><a href=https://tc39.es/ecma262/#sec-getfunctionrealm>GetFunctionRealm</a></dfn> abstract operation<li>The <dfn id=hasownproperty><a href=https://tc39.es/ecma262/#sec-hasownproperty>HasOwnProperty</a></dfn> abstract operation<li>The <dfn id=js-hostcalljobcallback><a href=https://tc39.es/ecma262/#sec-hostcalljobcallback>HostCallJobCallback</a></dfn> abstract operation<li>The <dfn id=js-hostenqueuefinalizationregistrycleanupjob><a href=https://tc39.es/ecma262/#sec-host-cleanup-finalization-registry>HostEnqueueFinalizationRegistryCleanupJob</a></dfn> abstract operation<li>The <dfn id=js-hostenqueuegenericjob><a href=https://tc39.es/ecma262/#sec-hostenqueuegenericjob>HostEnqueueGenericJob</a></dfn> abstract operation<li>The <dfn id=js-hostenqueuepromisejob><a href=https://tc39.es/ecma262/#sec-hostenqueuepromisejob>HostEnqueuePromiseJob</a></dfn> abstract operation<li>The <dfn id=js-hostenqueuetimeoutjob><a href=https://tc39.es/ecma262/#sec-hostenqueuetimeoutjob>HostEnqueueTimeoutJob</a></dfn> abstract operation<li>The <dfn id=js-hostensurecanaddprivateelement><a href=https://tc39.es/ecma262/#sec-hostensurecanaddprivateelement>HostEnsureCanAddPrivateElement</a></dfn> abstract operation<li>The <dfn id=js-hostgetsupportedimportattributes><a href=https://tc39.es/ecma262/#sec-hostgetsupportedimportattributes>HostGetSupportedImportAttributes</a></dfn> abstract operation<li>The <dfn id=js-hostloadimportedmodule><a href=https://tc39.es/ecma262/#sec-HostLoadImportedModule>HostLoadImportedModule</a></dfn> abstract operation<li>The <dfn id=js-hostmakejobcallback><a href=https://tc39.es/ecma262/#sec-hostmakejobcallback>HostMakeJobCallback</a></dfn> abstract operation<li>The <dfn id=js-hostpromiserejectiontracker><a href=https://tc39.es/ecma262/#sec-host-promise-rejection-tracker>HostPromiseRejectionTracker</a></dfn> abstract operation<li>The <dfn id=js-initializehostdefinedrealm><a href=https://tc39.es/ecma262/#sec-initializehostdefinedrealm>InitializeHostDefinedRealm</a></dfn> abstract operation<li>The <dfn id=isarraybufferviewoutofbounds><a href=https://tc39.es/ecma262/#sec-isarraybufferviewoutofbounds>IsArrayBufferViewOutOfBounds</a></dfn> abstract operation<li>The <dfn id=isaccessordescriptor><a href=https://tc39.es/ecma262/#sec-isaccessordescriptor>IsAccessorDescriptor</a></dfn> abstract operation<li>The <dfn id=iscallable><a href=https://tc39.es/ecma262/#sec-iscallable>IsCallable</a></dfn> abstract operation<li>The <dfn id=isconstructor><a href=https://tc39.es/ecma262/#sec-isconstructor>IsConstructor</a></dfn> abstract operation<li>The <dfn id=isdatadescriptor><a href=https://tc39.es/ecma262/#sec-isdatadescriptor>IsDataDescriptor</a></dfn> abstract operation<li>The <dfn id=isdetachedbuffer><a href=https://tc39.es/ecma262/#sec-isdetachedbuffer>IsDetachedBuffer</a></dfn> abstract operation<li>The <dfn id=issharedarraybuffer><a href=https://tc39.es/ecma262/#sec-issharedarraybuffer>IsSharedArrayBuffer</a></dfn> abstract operation<li>The <dfn id=js-newobjectenvironment><a href=https://tc39.es/ecma262/#sec-newobjectenvironment>NewObjectEnvironment</a></dfn> abstract operation<li>The <dfn id=normalcompletion><a href=https://tc39.es/ecma262/#sec-normalcompletion>NormalCompletion</a></dfn> abstract operation<li>The <dfn id=ordinarygetprototypeof><a href=https://tc39.es/ecma262/#sec-ordinarygetprototypeof>OrdinaryGetPrototypeOf</a></dfn> abstract operation<li>The <dfn id=ordinarysetprototypeof><a href=https://tc39.es/ecma262/#sec-ordinarysetprototypeof>OrdinarySetPrototypeOf</a></dfn> abstract operation<li>The <dfn id=ordinaryisextensible><a href=https://tc39.es/ecma262/#sec-ordinaryisextensible>OrdinaryIsExtensible</a></dfn> abstract operation<li>The <dfn id=ordinarypreventextensions><a href=https://tc39.es/ecma262/#sec-ordinarypreventextensions>OrdinaryPreventExtensions</a></dfn> abstract operation<li>The <dfn id=ordinarygetownproperty><a href=https://tc39.es/ecma262/#sec-ordinarygetownproperty>OrdinaryGetOwnProperty</a></dfn> abstract operation<li>The <dfn id=ordinarydefineownproperty><a href=https://tc39.es/ecma262/#sec-ordinarydefineownproperty>OrdinaryDefineOwnProperty</a></dfn> abstract operation<li>The <dfn id=ordinaryget><a href=https://tc39.es/ecma262/#sec-ordinaryget>OrdinaryGet</a></dfn> abstract operation<li>The <dfn id=ordinaryset><a href=https://tc39.es/ecma262/#sec-ordinaryset>OrdinarySet</a></dfn> abstract operation<li>The <dfn id=ordinarydelete><a href=https://tc39.es/ecma262/#sec-ordinarydelete>OrdinaryDelete</a></dfn> abstract operation<li>The <dfn id=ordinaryownpropertykeys><a href=https://tc39.es/ecma262/#sec-ordinaryownpropertykeys>OrdinaryOwnPropertyKeys</a></dfn> abstract operation<li>The <dfn id=ordinaryobjectcreate><a href=https://tc39.es/ecma262/#sec-objectcreate>OrdinaryObjectCreate</a></dfn> abstract operation<li>The <dfn id=parsejsonmodule><a href=https://tc39.es/ecma262/#sec-parse-json-module>ParseJSONModule</a></dfn> abstract operation<li>The <dfn id=js-parsemodule><a href=https://tc39.es/ecma262/#sec-parsemodule>ParseModule</a></dfn> abstract operation<li>The <dfn id=js-parsescript><a href=https://tc39.es/ecma262/#sec-parse-script>ParseScript</a></dfn> abstract operation<li>The <dfn id=newpromisereactionjob><a href=https://tc39.es/ecma262/#sec-newpromisereactionjob>NewPromiseReactionJob</a></dfn> abstract operation<li>The <dfn id=newpromiseresolvethenablejob><a href=https://tc39.es/ecma262/#sec-newpromiseresolvethenablejob>NewPromiseResolveThenableJob</a></dfn> abstract operation<li>The <dfn id=regexpbuiltinexec><a href=https://tc39.es/ecma262/#sec-regexpbuiltinexec>RegExpBuiltinExec</a></dfn> abstract operation<li>The <dfn id=regexpcreate><a href=https://tc39.es/ecma262/#sec-regexpcreate>RegExpCreate</a></dfn> abstract operation<li>The <dfn id=runjobs><a href=https://tc39.es/ecma262/#sec-runjobs>RunJobs</a></dfn> abstract operation<li>The <dfn id=samevalue><a href=https://tc39.es/ecma262/#sec-samevalue>SameValue</a></dfn> abstract operation<li>The <dfn id=js-scriptevaluation><a href=https://tc39.es/ecma262/#sec-runtime-semantics-scriptevaluation>ScriptEvaluation</a></dfn> abstract operation<li>The <dfn id=setsyntheticmoduleexport><a href=https://tc39.es/ecma262/#sec-setsyntheticmoduleexport>SetSyntheticModuleExport</a></dfn> abstract operation<li>The <dfn id=setimmutableprototype><a href=https://tc39.es/ecma262/#sec-set-immutable-prototype>SetImmutablePrototype</a></dfn> abstract operation<li>The <dfn id=throwcompletion><a href=https://tc39.es/ecma262/#sec-throwcompletion>ThrowCompletion</a></dfn> abstract operation<li>The <dfn id=js-toboolean><a href=https://tc39.es/ecma262/#sec-toboolean>ToBoolean</a></dfn> abstract operation<li>The <dfn id=tostring><a href=https://tc39.es/ecma262/#sec-tostring>ToString</a></dfn> abstract operation<li>The <dfn id=touint32><a href=https://tc39.es/ecma262/#sec-touint32>ToUint32</a></dfn> abstract operation<li>The <dfn id=typedarraycreate><a href=https://tc39.es/ecma262/#typedarray-create>TypedArrayCreate</a></dfn> abstract operation<li>The <dfn id=js-abstract-equality><a href=https://tc39.es/ecma262/#sec-islooselyequal>IsLooselyEqual</a></dfn> abstract operation<li>The <dfn id=js-strict-equality><a href=https://tc39.es/ecma262/#sec-isstrictlyequal>IsStrictlyEqual</a></dfn> abstract operation<li>The <dfn id=atomics><a href=https://tc39.es/ecma262/#sec-atomics-object><code>Atomics</code></a></dfn> object<li>The <dfn id=atomics.waitasync><a href=https://tc39.es/ecma262/#sec-atomics.waitasync><code>Atomics.waitAsync</code></a></dfn> object<li>The <dfn id=date><a href=https://tc39.es/ecma262/#sec-date-objects><code>Date</code></a></dfn> class<li>The <dfn id=finalizationregistry><a href=https://tc39.es/ecma262/#sec-finalization-registry-objects><code>FinalizationRegistry</code></a></dfn> class<li>The <dfn id=regexp><a href=https://tc39.es/ecma262/#sec-regexp-regular-expression-objects><code>RegExp</code></a></dfn> class<li>The <dfn id=sharedarraybuffer><a href=https://tc39.es/ecma262/#sec-sharedarraybuffer-objects><code>SharedArrayBuffer</code></a></dfn> class<li>The <dfn id=syntaxerror-2><a href=https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-syntaxerror><code>SyntaxError</code></a></dfn> class<li>The <dfn id=typeerror><a href=https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-typeerror><code>TypeError</code></a></dfn> class<li>The <dfn id=js-rangeerror><a href=https://tc39.es/ecma262/#sec-native-error-types-used-in-this-standard-rangeerror><code>RangeError</code></a></dfn> class<li>The <dfn id=weakref><a href=https://tc39.es/ecma262/#sec-weak-ref-objects><code>WeakRef</code></a></dfn> class<li>The <dfn id=eval()><a href=https://tc39.es/ecma262/#sec-eval-x><code>eval()</code></a></dfn> function<li>The <dfn id=weakref.prototype.deref()><a href=https://tc39.es/ecma262/#sec-weak-ref.prototype.deref><code>WeakRef.prototype.deref()</code></a></dfn> function<li>The <dfn id=ishtmldda><a href=https://tc39.es/ecma262/#sec-IsHTMLDDA-internal-slot>[[IsHTMLDDA]]</a></dfn> internal slot<li><dfn id=import()><a href=https://tc39.es/ecma262/#sec-import-calls><code>import()</code></a></dfn><li><dfn id=import.meta><a href=https://tc39.es/ecma262/#sec-meta-properties><code>import.meta</code></a></dfn><li>The <dfn id=js-hostgetimportmetaproperties><a href=https://tc39.es/ecma262/#sec-hostgetimportmetaproperties>HostGetImportMetaProperties</a></dfn> abstract operation<li>The <dfn id=js-typeof><a href=https://tc39.es/ecma262/#sec-typeof-operator><code>typeof</code></a></dfn> operator<li>The <dfn id=delete><a href=https://tc39.es/ecma262/#sec-delete-operator><code>delete</code></a></dfn> operator<li><dfn id=the-typedarray-constructors><a href=https://tc39.es/ecma262/#table-49>The <var>TypedArray</var> Constructors</a></dfn> table</ul>

    <p>User agents that support JavaScript must also implement the <cite>Dynamic Code Brand
    Checks</cite> proposal. The following terms are defined there, and used in this specification:
    <a href=references.html#refsJSDYNAMICCODEBRANDCHECKS>[JSDYNAMICCODEBRANDCHECKS]</a></p>

    <ul class=brief><li>The <dfn id=js-hostensurecancompilestrings><a href=https://tc39.es/proposal-dynamic-code-brand-checks/#sec-hostensurecancompilestrings>HostEnsureCanCompileStrings</a></dfn> abstract operation<li>The <dfn id=js-hostgetcodeforeval><a href=https://tc39.es/proposal-dynamic-code-brand-checks/#sec-hostgetcodeforeval>HostGetCodeForEval</a></dfn> abstract operation</ul>

    <p>User agents that support JavaScript must also implement <cite>ECMAScript
    Internationalization API</cite>. <a href=references.html#refsJSINTL>[JSINTL]</a></p>

    <p>User agents that support JavaScript must also implement the <cite>Temporal</cite> proposal.
    The following terms are defined there, and used in this specification: <a href=references.html#refsJSTEMPORAL>[JSTEMPORAL]</a></p>

    <ul class=brief><li>The <dfn id=js-hostsystemutcepochnanoseconds><a href=https://tc39.es/proposal-temporal/#sec-hostsystemutcepochnanoseconds>HostSystemUTCEpochNanoseconds</a></dfn> abstract operation<li>The <dfn id=nsmaxinstant><a href=https://tc39.es/proposal-temporal/#eqn-nsMaxInstant>nsMaxInstant</a></dfn> and
         <dfn id=nsmininstant><a href=https://tc39.es/proposal-temporal/#eqn-nsMinInstant>nsMinInstant</a></dfn> values</ul>
   <dt>WebAssembly<dd>
    <p>The following term is defined in <cite>WebAssembly JavaScript Interface</cite>:
    <a href=references.html#refsWASMJS>[WASMJS]</a></p>

    <ul class=brief><li><dfn id=webassembly.module><a href=https://webassembly.github.io/spec/js-api/#module><code>WebAssembly.Module</code></a></dfn></ul>
   <dt>DOM<dd>
    <p>The Document Object Model (DOM) is a representation — a model — of a document and
    its content. The DOM is not just an API; the conformance criteria of HTML implementations are
    defined, in this specification, in terms of operations on the DOM. <a href=references.html#refsDOM>[DOM]</a></p>

    <p>Implementations must support DOM and the events defined in UI Events, because this
    specification is defined in terms of the DOM, and some of the features are defined as extensions
    to the DOM interfaces. <a href=references.html#refsDOM>[DOM]</a> <a href=references.html#refsUIEVENTS>[UIEVENTS]</a></p>

    <p>In particular, the following features are defined in <cite>DOM</cite>: <a href=references.html#refsDOM>[DOM]</a></p>

    <ul class=brief><li><dfn id=attr><a href=https://dom.spec.whatwg.org/#interface-attr><code>Attr</code></a></dfn> interface<li><dfn id=characterdata><a href=https://dom.spec.whatwg.org/#interface-characterdata><code>CharacterData</code></a></dfn> interface<li><dfn id=comment-2><a href=https://dom.spec.whatwg.org/#interface-comment><code>Comment</code></a></dfn> interface<li><dfn id=domimplementation><a href=https://dom.spec.whatwg.org/#interface-domimplementation><code>DOMImplementation</code></a></dfn> interface<li><dfn id=dom-document><a href=https://dom.spec.whatwg.org/#interface-document><code>Document</code></a></dfn> interface and its
         <dfn id=dom-document-doctype><a href=https://dom.spec.whatwg.org/#dom-document-doctype><code>doctype</code></a></dfn> attribute
     <li><dfn id=dom-documentorshadowroot><a href=https://dom.spec.whatwg.org/#documentorshadowroot><code>DocumentOrShadowRoot</code></a></dfn> interface<li><dfn id=documentfragment><a href=https://dom.spec.whatwg.org/#interface-documentfragment><code>DocumentFragment</code></a></dfn> interface<li><dfn id=documenttype><a href=https://dom.spec.whatwg.org/#interface-documenttype><code>DocumentType</code></a></dfn> interface<li><dfn id=childnode><a href=https://dom.spec.whatwg.org/#interface-childnode><code>ChildNode</code></a></dfn> interface<li><dfn id=element><a href=https://dom.spec.whatwg.org/#interface-element><code>Element</code></a></dfn> interface<li><dfn id=dom-element-attachshadow><a href=https://dom.spec.whatwg.org/#dom-element-attachshadow><code>attachShadow()</code></a></dfn> method.<li>An element's <dfn id=concept-element-shadow-root><a href=https://dom.spec.whatwg.org/#concept-element-shadow-root>shadow root</a></dfn><li>A <a href=https://dom.spec.whatwg.org/#concept-element-shadow-root id=dependencies:concept-element-shadow-root data-x-internal=concept-element-shadow-root>shadow root</a>'s <dfn id=concept-shadow-root-mode><a href=https://dom.spec.whatwg.org/#shadowroot-mode>mode</a></dfn><li>A <a href=https://dom.spec.whatwg.org/#concept-element-shadow-root id=dependencies:concept-element-shadow-root-2 data-x-internal=concept-element-shadow-root>shadow root</a>'s <dfn id=concept-shadow-root-declarative><a href=https://dom.spec.whatwg.org/#shadowroot-declarative>declarative</a></dfn> member<li>The <dfn id=concept-attach-a-shadow-root><a href=https://dom.spec.whatwg.org/#concept-attach-a-shadow-root>attach a shadow root</a></dfn> algorithm<li>The <dfn id=dom-retarget><a href=https://dom.spec.whatwg.org/#retarget>retargeting algorithm</a></dfn><li><dfn id=node><a href=https://dom.spec.whatwg.org/#interface-node><code>Node</code></a></dfn> interface<li><dfn id=nodelist><a href=https://dom.spec.whatwg.org/#interface-nodelist><code>NodeList</code></a></dfn> interface<li><dfn id=processinginstruction><a href=https://dom.spec.whatwg.org/#interface-processinginstruction><code>ProcessingInstruction</code></a></dfn> interface<li><dfn id=shadowroot><a href=https://dom.spec.whatwg.org/#interface-shadowroot><code>ShadowRoot</code></a></dfn> interface<li><dfn id=text><a href=https://dom.spec.whatwg.org/#interface-text><code>Text</code></a></dfn> interface<li><dfn id=range><a href=https://dom.spec.whatwg.org/#interface-range><code>Range</code></a></dfn> interface<li><dfn id=node-document><a href=https://dom.spec.whatwg.org/#concept-node-document>node document</a></dfn> concept<li><dfn id=concept-document-type><a href=https://dom.spec.whatwg.org/#concept-document-type>document type</a></dfn> concept<li><dfn id=concept-documentfragment-host><a href=https://dom.spec.whatwg.org/#concept-documentfragment-host>host</a></dfn> concept<li>The <dfn id=shadow-root><a href=https://dom.spec.whatwg.org/#concept-shadow-root>shadow root</a></dfn> concept, and its <dfn id=delegates-focus><a href=https://dom.spec.whatwg.org/#shadowroot-delegates-focus>delegates focus</a></dfn>, <dfn id=available-to-element-internals><a href=https://dom.spec.whatwg.org/#shadowroot-available-to-element-internals>available to element internals</a></dfn>, <dfn id=clonable><a href=https://dom.spec.whatwg.org/#shadowroot-clonable>clonable</a></dfn>, <dfn id=shadow-serializable><a href=https://dom.spec.whatwg.org/#shadowroot-serializable>serializable</a></dfn>, <dfn id=shadow-root-custom-element-registry><a href=https://dom.spec.whatwg.org/#shadowroot-custom-element-registry>custom element registry</a></dfn>, and <dfn id=keep-custom-element-registry-null><a href=https://dom.spec.whatwg.org/#shadowroot-keep-custom-element-registry-null>keep custom element registry null</a></dfn>.<li>The <dfn id=shadow-host><a href=https://dom.spec.whatwg.org/#element-shadow-host>shadow host</a></dfn> concept<li><dfn id=htmlcollection><a href=https://dom.spec.whatwg.org/#interface-htmlcollection><code>HTMLCollection</code></a></dfn> interface, its
         <dfn id=dom-htmlcollection-length><a href=https://dom.spec.whatwg.org/#dom-htmlcollection-length><code>length</code></a></dfn> attribute, and its
         <dfn id=dom-htmlcollection-item><a href=https://dom.spec.whatwg.org/#dom-htmlcollection-item><code>item()</code></a></dfn> and
         <dfn id=dom-htmlcollection-nameditem><a href=https://dom.spec.whatwg.org/#dom-htmlcollection-nameditem><code>namedItem()</code></a></dfn> methods<li>The terms <dfn id=concept-collection><a href=https://dom.spec.whatwg.org/#concept-collection>collection</a></dfn> and <dfn id=represented-by-the-collection><a href=https://dom.spec.whatwg.org/#represented-by-the-collection>represented by the collection</a></dfn><li><dfn id=domtokenlist><a href=https://dom.spec.whatwg.org/#interface-domtokenlist><code>DOMTokenList</code></a></dfn> interface, and its
         <dfn id=dom-domtokenlist-value><a href=https://dom.spec.whatwg.org/#dom-domtokenlist-value><code>value</code></a></dfn> attribute and
         <dfn id=dom-domtokenlist-supports><a href=https://dom.spec.whatwg.org/#dom-domtokenlist-supports><code>supports</code></a></dfn> operation<li><dfn id=dom-domimplementation-createdocument><a href=https://dom.spec.whatwg.org/#dom-domimplementation-createdocument><code>createDocument()</code></a></dfn> method<li><dfn id=dom-domimplementation-createhtmldocument><a href=https://dom.spec.whatwg.org/#dom-domimplementation-createhtmldocument><code>createHTMLDocument()</code></a></dfn> method<li><dfn id=dom-document-createelement><a href=https://dom.spec.whatwg.org/#dom-document-createelement><code>createElement()</code></a></dfn> method<li><dfn id=dom-document-createelementns><a href=https://dom.spec.whatwg.org/#dom-document-createelementns><code>createElementNS()</code></a></dfn> method<li><dfn id=dom-document-getelementbyid><a href=https://dom.spec.whatwg.org/#dom-nonelementparentnode-getelementbyid><code>getElementById()</code></a></dfn> method<li><dfn id=dom-document-getelementsbyclassname><a href=https://dom.spec.whatwg.org/#dom-document-getelementsbyclassname><code>getElementsByClassName()</code></a></dfn> method<li><dfn id=dom-node-append><a href=https://dom.spec.whatwg.org/#dom-node-append><code>append()</code></a></dfn> method<li><dfn id=dom-node-appendchild><a href=https://dom.spec.whatwg.org/#dom-node-appendchild><code>appendChild()</code></a></dfn> method<li><dfn id=dom-node-clonenode><a href=https://dom.spec.whatwg.org/#dom-node-clonenode><code>cloneNode()</code></a></dfn> method<li><dfn id=dom-parentnode-movebefore><a href=https://dom.spec.whatwg.org/#dom-parentnode-movebefore><code>moveBefore()</code></a></dfn> method<li><dfn id=dom-document-importnode><a href=https://dom.spec.whatwg.org/#dom-document-importnode><code>importNode()</code></a></dfn> method<li><dfn id=dom-event-preventdefault><a href=https://dom.spec.whatwg.org/#dom-event-preventdefault><code>preventDefault()</code></a></dfn> method<li><dfn id=dom-element-id><a href=https://dom.spec.whatwg.org/#dom-element-id><code>id</code></a></dfn> attribute<li><dfn id=dom-element-setattribute><a href=https://dom.spec.whatwg.org/#dom-element-setattribute><code>setAttribute()</code></a></dfn> method<li><dfn id=textcontent><a href=https://dom.spec.whatwg.org/#dom-node-textcontent><code>textContent</code></a></dfn> attribute<li>The <dfn id=tree><a href=https://dom.spec.whatwg.org/#concept-tree>tree</a></dfn>, <dfn id=shadow-tree><a href=https://dom.spec.whatwg.org/#concept-shadow-tree>shadow tree</a></dfn>, and <dfn id=node-tree><a href=https://dom.spec.whatwg.org/#concept-node-tree>node tree</a></dfn> concepts<li>The <dfn id=tree-order><a href=https://dom.spec.whatwg.org/#concept-tree-order>tree order</a></dfn> and <dfn id=shadow-including-tree-order><a href=https://dom.spec.whatwg.org/#concept-shadow-including-tree-order>shadow-including tree order</a></dfn> concepts<li>The <dfn id=concept-element><a href=https://dom.spec.whatwg.org/#concept-element>element</a></dfn> concept<li>The <dfn id=concept-tree-child><a href=https://dom.spec.whatwg.org/#concept-tree-child>child</a></dfn> concept<li>The <dfn id=root><a href=https://dom.spec.whatwg.org/#concept-tree-root>root</a></dfn> and <dfn id=shadow-including-root><a href=https://dom.spec.whatwg.org/#concept-shadow-including-root>shadow-including root</a></dfn> concepts<li>The <dfn id=inclusive-ancestor><a href=https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor>inclusive ancestor</a></dfn>,
             <dfn id=ancestor><a href=https://dom.spec.whatwg.org/#concept-tree-ancestor>ancestor</a></dfn>,
             <dfn id=descendant><a href=https://dom.spec.whatwg.org/#concept-tree-descendant>descendant</a></dfn>,
             <dfn id=concept-shadow-including-ancestor><a href=https://dom.spec.whatwg.org/#concept-shadow-including-ancestor>shadow-including ancestor</a></dfn>,
             <dfn id=shadow-including-descendant><a href=https://dom.spec.whatwg.org/#concept-shadow-including-descendant>shadow-including descendant</a></dfn>,
             <dfn id=shadow-including-inclusive-descendant><a href=https://dom.spec.whatwg.org/#concept-shadow-including-inclusive-descendant>shadow-including inclusive descendant</a></dfn>, and
             <dfn id=shadow-including-inclusive-ancestor><a href=https://dom.spec.whatwg.org/#concept-shadow-including-inclusive-ancestor>shadow-including inclusive ancestor</a></dfn> concepts<li>The <dfn id=first-child><a href=https://dom.spec.whatwg.org/#concept-tree-first-child>first child</a></dfn>,
             <dfn id=last-child><a href=https://dom.spec.whatwg.org/#concept-tree-last-child>last child</a></dfn>,
             <dfn id=next-sibling><a href=https://dom.spec.whatwg.org/#concept-tree-next-sibling>next sibling</a></dfn>,
             <dfn id=previous-sibling><a href=https://dom.spec.whatwg.org/#concept-tree-previous-sibling>previous sibling</a></dfn>, and
             <dfn id=parent><a href=https://dom.spec.whatwg.org/#concept-tree-parent>parent</a></dfn> concepts<li>The <dfn id=parent-element><a href=https://dom.spec.whatwg.org/#parent-element>parent element</a></dfn> concept<li>The <dfn id=document-element><a href=https://dom.spec.whatwg.org/#document-element>document element</a></dfn> concept<li>The <dfn id=in-a-document-tree><a href=https://dom.spec.whatwg.org/#in-a-document-tree>in a document tree</a></dfn>, <dfn id=in-a-document><a href=https://dom.spec.whatwg.org/#in-a-document>in a document</a></dfn> (legacy), and <dfn id=connected><a href=https://dom.spec.whatwg.org/#connected>connected</a></dfn> concepts<li>The <dfn id=concept-slot><a href=https://dom.spec.whatwg.org/#concept-slot>slot</a></dfn> concept, and its <dfn id=slot-name><a href=https://dom.spec.whatwg.org/#slot-name>name</a></dfn> and <dfn id=assigned-nodes><a href=https://dom.spec.whatwg.org/#slot-assigned-nodes>assigned nodes</a></dfn><li>The <dfn id=assigned-slot><a href=https://dom.spec.whatwg.org/#slotable-assigned-slot>assigned slot</a></dfn> concept<li>The <dfn id=slot-assignment><a href=https://dom.spec.whatwg.org/#dom-shadowroot-slot-assignment>slot assignment</a></dfn> concept<li>The <dfn id=slottable><a href=https://dom.spec.whatwg.org/#concept-slotable>slottable</a></dfn> concept<li>The <dfn id=assign-slottables-for-a-tree><a href=https://dom.spec.whatwg.org/#assign-slotables-for-a-tree>assign slottables for a tree</a></dfn> algorithm<li>The <dfn id=event-slotchange><a href=https://dom.spec.whatwg.org/#eventdef-htmlslotelement-slotchange><code>slotchange</code></a></dfn> event<li>The <dfn id=inclusive-descendant><a href=https://dom.spec.whatwg.org/#concept-tree-inclusive-descendant>inclusive descendant</a></dfn> concept<li>The <dfn id=finding-flattened-slottables><a href=https://dom.spec.whatwg.org/#find-flattened-slotables>find flattened slottables</a></dfn> algorithm<li>The <dfn id=manual-slot-assignment><a href=https://dom.spec.whatwg.org/#slottable-manual-slot-assignment>manual slot assignment</a></dfn> concept<li>The <dfn id=assign-a-slot><a href=https://dom.spec.whatwg.org/#assign-a-slot>assign a slot</a></dfn> algorithm<li>The <dfn id=pre-insert><a href=https://dom.spec.whatwg.org/#concept-node-pre-insert>pre-insert</a></dfn>, <dfn id=concept-node-insert><a href=https://dom.spec.whatwg.org/#concept-node-insert>insert</a></dfn>, <dfn id=concept-node-append><a href=https://dom.spec.whatwg.org/#concept-node-append>append</a></dfn>, <dfn id=concept-node-replace><a href=https://dom.spec.whatwg.org/#concept-node-replace>replace</a></dfn>, <dfn id=concept-node-replace-all><a href=https://dom.spec.whatwg.org/#concept-node-replace-all>replace all</a></dfn>, <dfn id=string-replace-all><a href=https://dom.spec.whatwg.org/#string-replace-all>string replace all</a></dfn>, <dfn id=concept-node-remove><a href=https://dom.spec.whatwg.org/#concept-node-remove>remove</a></dfn>, and <dfn id=concept-node-adopt><a href=https://dom.spec.whatwg.org/#concept-node-adopt>adopt</a></dfn> algorithms for nodes<li>The <dfn id=concept-tree-descendant><a href=https://dom.spec.whatwg.org/#concept-tree-descendant>descendant</a></dfn> concept<li>The <dfn id=concept-node-insert-ext><a href=https://dom.spec.whatwg.org/#concept-node-insert-ext>insertion steps</a></dfn>,
     <li>The <dfn id=concept-node-post-connection-ext><a href=https://dom.spec.whatwg.org/#concept-node-post-connection-ext>post-connection steps</a></dfn>,
             <dfn id=concept-node-remove-ext><a href=https://dom.spec.whatwg.org/#concept-node-remove-ext>removing steps</a></dfn>,
             <dfn id=concept-node-move-ext><a href=https://dom.spec.whatwg.org/#concept-node-move-ext>moving steps</a></dfn>,
             <dfn id=concept-node-adopt-ext><a href=https://dom.spec.whatwg.org/#concept-node-adopt-ext>adopting steps</a></dfn>, and
             <dfn id=children-changed-steps><a href=https://dom.spec.whatwg.org/#concept-node-children-changed-ext>children changed steps</a></dfn> hooks for elements<li>The <dfn id=concept-element-attributes-change><a href=https://dom.spec.whatwg.org/#concept-element-attributes-change>change</a></dfn>, <dfn id=concept-element-attributes-append><a href=https://dom.spec.whatwg.org/#concept-element-attributes-append>append</a></dfn>, <dfn id=concept-element-attributes-remove><a href=https://dom.spec.whatwg.org/#concept-element-attributes-remove>remove</a></dfn>, <dfn id=concept-element-attributes-replace><a href=https://dom.spec.whatwg.org/#concept-element-attributes-replace>replace</a></dfn>, <dfn id=concept-element-attributes-get-by-namespace><a href=https://dom.spec.whatwg.org/#concept-element-attributes-get-by-namespace>get an attribute by namespace and local name</a></dfn>, <dfn id=concept-element-attributes-set-value><a href=https://dom.spec.whatwg.org/#concept-element-attributes-set-value>set value</a></dfn>, and <dfn id=concept-element-attributes-remove-by-namespace><a href=https://dom.spec.whatwg.org/#concept-element-attributes-remove-by-namespace>remove an attribute by namespace and local name</a></dfn> algorithms for attributes<li>The <dfn id=concept-element-attributes-change-ext><a href=https://dom.spec.whatwg.org/#concept-element-attributes-change-ext>attribute change steps</a></dfn> hook for attributes<li>The <dfn id=concept-attribute-value><a href=https://dom.spec.whatwg.org/#concept-attribute-value>value</a></dfn> concept for attributes<li>The <dfn id=concept-attribute-local-name><a href=https://dom.spec.whatwg.org/#concept-attribute-local-name>local name</a></dfn> concept for attributes<li>The <dfn id=attribute-list><a href=https://dom.spec.whatwg.org/#concept-element-attribute>attribute list</a></dfn> concept<li>The <dfn id=concept-cd-data><a href=https://dom.spec.whatwg.org/#concept-cd-data>data</a></dfn> of a <code id=dependencies:characterdata><a data-x-internal=characterdata href=https://dom.spec.whatwg.org/#interface-characterdata>CharacterData</a></code> node and its
             <dfn id=replace-data><a href=https://dom.spec.whatwg.org/#concept-cd-replace>replace data</a></dfn> algorithm<li>The <dfn id=child-text-content><a href=https://dom.spec.whatwg.org/#concept-child-text-content>child text content</a></dfn> of a node<li>The <dfn id=descendant-text-content><a href=https://dom.spec.whatwg.org/#concept-descendant-text-content>descendant text content</a></dfn> of a node<li>The <dfn id=concept-doctype-name><a href=https://dom.spec.whatwg.org/#concept-doctype-name>name</a></dfn>,
             <dfn id=concept-doctype-publicid><a href=https://dom.spec.whatwg.org/#concept-doctype-publicid>public ID</a></dfn>, and
             <dfn id=concept-doctype-systemid><a href=https://dom.spec.whatwg.org/#concept-doctype-systemid>system ID</a></dfn> of a doctype<li><dfn id=event><a href=https://dom.spec.whatwg.org/#interface-event><code>Event</code></a></dfn> interface<li><dfn id=dom-event-constructor><a href=https://dom.spec.whatwg.org/#concept-event-constructor><code>Event</code> and derived interfaces constructor behavior</a></dfn><li><dfn id=eventtarget><a href=https://dom.spec.whatwg.org/#interface-eventtarget><code>EventTarget</code></a></dfn> interface<li>The <dfn id=activation-behaviour><a href=https://dom.spec.whatwg.org/#eventtarget-activation-behavior>activation behavior</a></dfn> hook<li>The <dfn id=legacy-pre-activation-behavior><a href=https://dom.spec.whatwg.org/#eventtarget-legacy-pre-activation-behavior>legacy-pre-activation behavior</a></dfn> hook<li>The <dfn id=legacy-canceled-activation-behavior><a href=https://dom.spec.whatwg.org/#eventtarget-legacy-canceled-activation-behavior>legacy-canceled-activation behavior</a></dfn> hook<li>The <dfn id=creating-an-event><a href=https://dom.spec.whatwg.org/#concept-event-create>create an event</a></dfn> algorithm<li>The <dfn id=concept-event-fire><a href=https://dom.spec.whatwg.org/#concept-event-fire>fire an event</a></dfn> algorithm<li>The <dfn id=canceled-flag><a href=https://dom.spec.whatwg.org/#canceled-flag>canceled flag</a></dfn><li>The <dfn id=dispatch-flag><a href=https://dom.spec.whatwg.org/#dispatch-flag>dispatch flag</a></dfn><li>The <dfn id=concept-event-dispatch><a href=https://dom.spec.whatwg.org/#concept-event-dispatch>dispatch</a></dfn> algorithm<li><dfn id=eventinit><a href=https://dom.spec.whatwg.org/#dictdef-eventinit><code>EventInit</code></a></dfn> dictionary type<li><dfn id=dom-event-type><a href=https://dom.spec.whatwg.org/#dom-event-type><code>type</code></a></dfn> attribute<li>An event's <dfn id=concept-event-target><a href=https://dom.spec.whatwg.org/#concept-event-target>target</a></dfn><li><dfn id=dom-event-currenttarget><a href=https://dom.spec.whatwg.org/#dom-event-currenttarget><code>currentTarget</code></a></dfn> attribute<li><dfn id=dom-event-bubbles><a href=https://dom.spec.whatwg.org/#dom-event-bubbles><code>bubbles</code></a></dfn> attribute<li><dfn id=dom-event-cancelable><a href=https://dom.spec.whatwg.org/#dom-event-cancelable><code>cancelable</code></a></dfn> attribute<li><dfn id=dom-event-composed><a href=https://dom.spec.whatwg.org/#dom-event-composed><code>composed</code></a></dfn> attribute<li><dfn id=composed-flag><a href=https://dom.spec.whatwg.org/#composed-flag>composed flag</a></dfn><li><dfn id=dom-event-istrusted><a href=https://dom.spec.whatwg.org/#dom-event-istrusted><code>isTrusted</code></a></dfn> attribute<li><dfn id=dom-event-initevent><a href=https://dom.spec.whatwg.org/#dom-event-initevent><code>initEvent()</code></a></dfn> method<li><dfn id=add-an-event-listener><a href=https://dom.spec.whatwg.org/#add-an-event-listener>add an event listener</a></dfn><li><dfn id=dom-eventtarget-addeventlistener><a href=https://dom.spec.whatwg.org/#dom-eventtarget-addeventlistener><code>addEventListener()</code></a></dfn> method<li>The <dfn id=remove-an-event-listener><a href=https://dom.spec.whatwg.org/#remove-an-event-listener>remove an event listener</a></dfn> and
             <dfn id=remove-all-event-listeners><a href=https://dom.spec.whatwg.org/#remove-all-event-listeners>remove all event listeners</a></dfn> algorithms<li><dfn id=dom-eventlistener><a href=https://dom.spec.whatwg.org/#callbackdef-eventlistener><code>EventListener</code></a></dfn> callback interface<li>The <dfn id=concept-event-type><a href=https://dom.spec.whatwg.org/#dom-event-type>type</a></dfn> of an event<li>An <dfn id=event-listener><a href=https://dom.spec.whatwg.org/#concept-event-listener>event listener</a></dfn> and its
            <dfn id=event-listener-type><a href=https://dom.spec.whatwg.org/#event-listener-type>type</a></dfn> and
            <dfn id=event-listener-callback><a href=https://dom.spec.whatwg.org/#event-listener-callback>callback</a></dfn><li>The <dfn id="document's-character-encoding"><a href=https://dom.spec.whatwg.org/#concept-document-encoding>encoding</a></dfn> (herein the <i>character encoding</i>),
             <dfn id=concept-document-mode><a href=https://dom.spec.whatwg.org/#concept-document-mode>mode</a></dfn>,
             <dfn id=document-custom-element-registry><a href=https://dom.spec.whatwg.org/#document-custom-element-registry>custom element registry</a></dfn>,
             <dfn id=concept-document-allow-declarative-shadow-roots><a href=https://dom.spec.whatwg.org/#concept-document-allow-declarative-shadow-roots>allow declarative shadow roots</a></dfn>, and
             <dfn id=concept-document-content-type><a href=https://dom.spec.whatwg.org/#concept-document-content-type>content type</a></dfn> of a <code id=dependencies:document><a href=dom.html#document>Document</a></code><li>The distinction between <dfn id=xml-documents><a href=https://dom.spec.whatwg.org/#xml-document>XML documents</a></dfn> and
                                 <dfn id=html-documents><a href=https://dom.spec.whatwg.org/#html-document>HTML documents</a></dfn><li>The terms <dfn id=quirks-mode><a href=https://dom.spec.whatwg.org/#concept-document-quirks>quirks mode</a></dfn>,
                   <dfn id=limited-quirks-mode><a href=https://dom.spec.whatwg.org/#concept-document-limited-quirks>limited-quirks mode</a></dfn>, and
                   <dfn id=no-quirks-mode><a href=https://dom.spec.whatwg.org/#concept-document-no-quirks>no-quirks mode</a></dfn><li>The algorithm <dfn id=concept-node-clone><a href=https://dom.spec.whatwg.org/#concept-node-clone>clone a node</a></dfn> with its arguments
                       <dfn id=concept-node-clone-document><a href=https://dom.spec.whatwg.org/#clone-a-node-document><var>document</var></a></dfn>,
                       <dfn id=concept-node-clone-subtree><a href=https://dom.spec.whatwg.org/#clone-a-node-subtree><var>subtree</var></a></dfn>,
                       <dfn id=concept-node-clone-parent><a href=https://dom.spec.whatwg.org/#clone-a-node-parent><var>parent</var></a></dfn>, and
                       <dfn id=concept-node-clone-fallbackregistry><a href=https://dom.spec.whatwg.org/#clone-a-node-fallbackregistry><var>fallbackRegistry</var></a></dfn>, and the concept of
                       <dfn id=concept-node-clone-ext><a href=https://dom.spec.whatwg.org/#concept-node-clone-ext>cloning steps</a></dfn><li>The concept of an element's <dfn id=concept-id><a href=https://dom.spec.whatwg.org/#concept-id>unique identifier (ID)</a></dfn><li>The concept of an element's <dfn id=concept-class><a href=https://dom.spec.whatwg.org/#concept-class>classes</a></dfn><li>The term <dfn id=concept-supported-tokens><a href=https://dom.spec.whatwg.org/#concept-supported-tokens>supported tokens</a></dfn><li>The concept of a DOM <dfn id=concept-range><a href=https://dom.spec.whatwg.org/#concept-range>range</a></dfn>, and the terms
                              <dfn id=concept-range-start-node><a href=https://dom.spec.whatwg.org/#concept-range-start-node>start node</a></dfn>,
                              <dfn id=concept-range-start><a href=https://dom.spec.whatwg.org/#concept-range-start>start</a></dfn>,
                              <dfn id=concept-range-end><a href=https://dom.spec.whatwg.org/#concept-range-end>end</a></dfn>, and
                              <dfn id=concept-range-bp><a href=https://dom.spec.whatwg.org/#concept-range-bp>boundary point</a></dfn> as applied to ranges.<li>The <dfn id=create-an-element><a href=https://dom.spec.whatwg.org/#concept-create-element>create an element</a></dfn> algorithm<li>The <dfn id=element-interface><a href=https://dom.spec.whatwg.org/#concept-element-interface>element interface</a></dfn> concept<li>The concepts of <dfn id=custom-element-state><a href=https://dom.spec.whatwg.org/#concept-element-custom-element-state>custom element state</a></dfn>, and of
                         <dfn id=concept-element-defined><a href=https://dom.spec.whatwg.org/#concept-element-defined>defined</a></dfn> and
                         <dfn id=concept-element-custom><a href=https://dom.spec.whatwg.org/#concept-element-custom>custom</a></dfn> elements<li>An element's <dfn id=concept-element-namespace><a href=https://dom.spec.whatwg.org/#concept-element-namespace>namespace</a></dfn>,
                      <dfn id=concept-element-namespace-prefix><a href=https://dom.spec.whatwg.org/#concept-element-namespace-prefix>namespace prefix</a></dfn>,
                      <dfn id=concept-element-local-name><a href=https://dom.spec.whatwg.org/#concept-element-local-name>local name</a></dfn>,
                      <dfn id=element-custom-element-registry><a href=https://dom.spec.whatwg.org/#element-custom-element-registry>custom element registry</a></dfn>,
                      <dfn id=concept-element-custom-element-definition><a href=https://dom.spec.whatwg.org/#concept-element-custom-element-definition>custom element definition</a></dfn>, and
                      <dfn id=concept-element-is-value><a href=https://dom.spec.whatwg.org/#concept-element-is-value><code>is</code> value</a></dfn><li><dfn id=mutationobserver><a href=https://dom.spec.whatwg.org/#mutationobserver><code>MutationObserver</code></a></dfn> interface and <dfn id=mutation-observers><a href=https://dom.spec.whatwg.org/#mutation-observers>mutation observers</a></dfn> in general<li><dfn id=abortcontroller><a href=https://dom.spec.whatwg.org/#abortcontroller><code>AbortController</code></a></dfn> and its
         <dfn id=concept-abortcontroller-signal><a href=https://dom.spec.whatwg.org/#abortcontroller-signal>signal</a></dfn><li><dfn id=abortsignal><a href=https://dom.spec.whatwg.org/#abortsignal><code>AbortSignal</code></a></dfn><li><dfn id=abortsignal-aborted><a href=https://dom.spec.whatwg.org/#abortsignal-aborted>aborted</a></dfn><li><dfn id=signal-abort><a href=https://dom.spec.whatwg.org/#abortcontroller-signal-abort>signal abort</a></dfn><li><dfn id=abortsignal-add><a href=https://dom.spec.whatwg.org/#abortsignal-add>add</a></dfn><li>The <dfn id=get-an-attribute-by-name><a href=https://dom.spec.whatwg.org/#concept-element-attributes-get-by-name>get an attribute by name</a></dfn> algorithm<li><dfn id=valid-attribute-local-name><a href=https://dom.spec.whatwg.org/#valid-attribute-local-name>valid attribute local name</a></dfn><li><dfn id=valid-element-local-name><a href=https://dom.spec.whatwg.org/#valid-element-local-name>valid element local name</a></dfn></ul>

    <p>The following features are defined in <cite>UI Events</cite>: <a href=references.html#refsUIEVENTS>[UIEVENTS]</a></p>

    <ul class=brief><li>The <dfn id=mouseevent><a href=https://w3c.github.io/uievents/#mouseevent><code>MouseEvent</code></a></dfn> interface<li>The <code id=dependencies:mouseevent><a data-x-internal=mouseevent href=https://w3c.github.io/uievents/#mouseevent>MouseEvent</a></code> interface's <dfn id=dom-mouseevent-relatedtarget><a href=https://w3c.github.io/uievents/#dom-mouseevent-relatedtarget><code>relatedTarget</code></a></dfn> attribute<li>The <code id=dependencies:mouseevent-2><a data-x-internal=mouseevent href=https://w3c.github.io/uievents/#mouseevent>MouseEvent</a></code> interface's <dfn id=dom-mouseevent-button><a href=https://w3c.github.io/uievents/#dom-mouseevent-button><code>button</code></a></dfn> attribute<li><dfn id=mouseeventinit><a href=https://w3c.github.io/uievents/#dictdef-mouseeventinit><code>MouseEventInit</code></a></dfn> dictionary type<li>The <dfn id=focusevent><a href=https://w3c.github.io/uievents/#focusevent><code>FocusEvent</code></a></dfn> interface<li>The <code id=dependencies:focusevent><a data-x-internal=focusevent href=https://w3c.github.io/uievents/#focusevent>FocusEvent</a></code> interface's <dfn id=dom-focusevent-relatedtarget><a href=https://w3c.github.io/uievents/#dom-focusevent-relatedtarget><code>relatedTarget</code></a></dfn> attribute<li>The <dfn id=uievent><a href=https://w3c.github.io/uievents/#uievent><code>UIEvent</code></a></dfn> interface<li>The <code id=dependencies:uievent><a data-x-internal=uievent href=https://w3c.github.io/uievents/#uievent>UIEvent</a></code> interface's <dfn id=dom-uievent-view><a href=https://w3c.github.io/uievents/#dom-uievent-view><code>view</code></a></dfn> attribute<li><dfn id=event-auxclick><a href=https://w3c.github.io/uievents/#event-type-auxclick><code>auxclick</code></a></dfn> event<li><dfn id=event-beforeinput><a href=https://w3c.github.io/uievents/#event-type-beforeinput><code>beforeinput</code></a></dfn> event<li><dfn id=event-click><a href=https://w3c.github.io/uievents/#event-type-click><code>click</code></a></dfn> event<li><dfn id=event-contextmenu><a href=https://w3c.github.io/uievents/#event-type-contextmenu><code>contextmenu</code></a></dfn> event<li><dfn id=event-dblclick><a href=https://w3c.github.io/uievents/#event-type-dblclick><code>dblclick</code></a></dfn> event<li><dfn id=event-input><a href=https://w3c.github.io/uievents/#event-type-input><code>input</code></a></dfn> event<li><dfn id=event-mousedown><a href=https://w3c.github.io/uievents/#event-type-mousedown><code>mousedown</code></a></dfn> event<li><dfn id=event-mouseenter><a href=https://w3c.github.io/uievents/#event-type-mouseenter><code>mouseenter</code></a></dfn> event<li><dfn id=event-mouseleave><a href=https://w3c.github.io/uievents/#event-type-mouseleave><code>mouseleave</code></a></dfn> event<li><dfn id=event-mousemove><a href=https://w3c.github.io/uievents/#event-type-mousemove><code>mousemove</code></a></dfn> event<li><dfn id=event-mouseout><a href=https://w3c.github.io/uievents/#event-type-mouseout><code>mouseout</code></a></dfn> event<li><dfn id=event-mouseover><a href=https://w3c.github.io/uievents/#event-type-mouseover><code>mouseover</code></a></dfn> event<li><dfn id=event-mouseup><a href=https://w3c.github.io/uievents/#event-type-mouseup><code>mouseup</code></a></dfn> event<li><dfn id=event-wheel><a href=https://w3c.github.io/uievents/#event-type-wheel><code>wheel</code></a></dfn> event<li><dfn id=event-keydown><a href=https://w3c.github.io/uievents/#event-type-keydown><code>keydown</code></a></dfn> event<li><dfn id=event-keypress><a href=https://w3c.github.io/uievents/#event-type-keypress><code>keypress</code></a></dfn> event<li><dfn id=event-keyup><a href=https://w3c.github.io/uievents/#event-type-keyup><code>keyup</code></a></dfn> event</ul>

    <p>The following features are defined in <cite>Touch Events</cite>: <a href=references.html#refsTOUCH>[TOUCH]</a></p>

    <ul class=brief><li><dfn id=touch><a href=https://w3c.github.io/touch-events/#touch-interface><code>Touch</code></a></dfn> interface<li><dfn id=touch-point><a href=https://w3c.github.io/touch-events/#dfn-touch-point>Touch point</a></dfn> concept<li><dfn id=event-touchend><a href=https://w3c.github.io/touch-events/#event-touchend><code>touchend</code></a></dfn> event</ul>

    <p>The following features are defined in <cite>Pointer Events</cite>:
    <a href=references.html#refsPOINTEREVENTS>[POINTEREVENTS]</a></p>

    <ul class=brief><li>The <dfn id=pointerevent><a href=https://w3c.github.io/pointerevents/#pointerevent-interface><code>PointerEvent</code></a></dfn> interface<li>The <code id=dependencies:pointerevent><a data-x-internal=pointerevent href=https://w3c.github.io/pointerevents/#pointerevent-interface>PointerEvent</a></code> interface's <dfn id=pointertype><a href=https://w3c.github.io/pointerevents/#dom-pointerevent-pointertype><code>pointerType</code></a></dfn> attribute<li><dfn id=fire-a-pointer-event><a href=https://w3c.github.io/pointerevents/#dfn-fire-a-pointer-event>fire a pointer event</a></dfn><li><dfn id=event-pointerdown><a href=https://w3c.github.io/pointerevents/#the-pointerdown-event><code>pointerdown</code></a></dfn> event<li><dfn id=event-pointerup><a href=https://w3c.github.io/pointerevents/#the-pointerup-event><code>pointerup</code></a></dfn> event<li><dfn id=event-pointercancel><a href=https://w3c.github.io/pointerevents/#the-pointercancel-event><code>pointercancel</code></a></dfn> event</ul>

    <p>The following events are defined in <cite>Clipboard API and events</cite>:
    <a href=references.html#refsCLIPBOARD-APIS>[CLIPBOARD-APIS]</a></p>

    <ul class=brief><li><dfn id=event-copy><a href=https://w3c.github.io/clipboard-apis/#clipboard-event-copy><code>copy</code></a></dfn> event<li><dfn id=event-cut><a href=https://w3c.github.io/clipboard-apis/#clipboard-event-cut><code>cut</code></a></dfn> event<li><dfn id=event-paste><a href=https://w3c.github.io/clipboard-apis/#clipboard-event-paste><code>paste</code></a></dfn> event</ul>

    <p>This specification sometimes uses the term <dfn>name</dfn> to refer to the event's
    <a href=https://dom.spec.whatwg.org/#dom-event-type id=dependencies:concept-event-type data-x-internal=concept-event-type>type</a>; as in, "an event named <code>click</code>" or "if the event name is <code>keypress</code>". The terms
    "name" and "type" for events are synonymous.</p>

    <p>The following features are defined in <cite>DOM Parsing and Serialization</cite>:
    <a href=references.html#refsDOMPARSING>[DOMPARSING]</a></p>

    <ul class=brief><li><dfn id=xml-serialization><a href=https://w3c.github.io/DOM-Parsing/#dfn-xml-serialization><code>XML serialization</code></a></dfn></ul>

    <p>The following features are defined in <cite>Selection API</cite>: <a href=references.html#refsSELECTION>[SELECTION]</a></p>

    <ul class=brief><li><dfn id=document-selection><a href=https://w3c.github.io/selection-api/#dfn-selection>selection</a></dfn><li><dfn id=selection><a href=https://w3c.github.io/selection-api/#selection-interface><code>Selection</code></a></dfn></ul>

    <p class=note>User agents are encouraged to implement the features described in
    <cite>execCommand</cite>. <a href=references.html#refsEXECCOMMAND>[EXECCOMMAND]</a></p>

    <p>The following features are defined in <cite>Fullscreen API</cite>: <a href=references.html#refsFULLSCREEN>[FULLSCREEN]</a></p>

    <ul class=brief><li><dfn id=dom-element-requestfullscreen><a href=https://fullscreen.spec.whatwg.org/#dom-element-requestfullscreen><code>requestFullscreen()</code></a></dfn><li><dfn id=event-fullscreenchange><a href=https://fullscreen.spec.whatwg.org/#eventdef-document-fullscreenchange><code>fullscreenchange</code></a></dfn><li><dfn id=run-the-fullscreen-steps><a href=https://fullscreen.spec.whatwg.org/#run-the-fullscreen-steps>run the fullscreen steps</a></dfn><li><dfn id=fully-exit-fullscreen><a href=https://fullscreen.spec.whatwg.org/#fully-exit-fullscreen>fully exit fullscreen</a></dfn><li><dfn id=fullscreen-element><a href=https://fullscreen.spec.whatwg.org/#fullscreen-element>fullscreen element</a></dfn><li><dfn id=fullscreen-flag><a href=https://fullscreen.spec.whatwg.org/#fullscreen-flag>fullscreen flag</a></dfn></ul>

    <p><cite>High Resolution Time</cite> provides the following features: <a href=references.html#refsHRT>[HRT]</a></p>

    <ul class=brief><li><dfn id=current-high-resolution-time><a href=https://w3c.github.io/hr-time/#dfn-current-high-resolution-time>current high resolution time</a></dfn><li><dfn id=relative-high-resolution-time><a href=https://w3c.github.io/hr-time/#dfn-relative-high-resolution-time>relative high resolution time</a></dfn><li><dfn id=unsafe-shared-current-time><a href=https://w3c.github.io/hr-time/#dfn-unsafe-shared-current-time>unsafe shared current time</a></dfn><li><dfn id=shared-monotonic-clock><a href=https://w3c.github.io/hr-time/#dfn-shared-monotonic-clock>shared monotonic clock</a></dfn><li><dfn id=unsafe-moment><a href=https://w3c.github.io/hr-time/#dfn-unsafe-moment>unsafe moment</a></dfn><li><dfn id=duration-from><a href=https://w3c.github.io/hr-time/#dfn-duration-from>duration from</a></dfn><li><dfn id=coarsen-time><a href=https://w3c.github.io/hr-time/#dfn-coarsen-time>coarsen time</a></dfn><li><dfn id=current-wall-time><a href=https://w3c.github.io/hr-time/#dfn-current-wall-time>current wall time</a></dfn><li><dfn id=unix-epoch><a href=https://w3c.github.io/hr-time/#dfn-unix-epoch>Unix epoch</a></dfn><li><dfn id=domhighrestimestamp><a href=https://w3c.github.io/hr-time/#dom-domhighrestimestamp><code>DOMHighResTimeStamp</code></a></dfn></ul>
   <dt>File API<dd>
    <p>This specification uses the following features defined in <cite>File API</cite>:
    <a href=references.html#refsFILEAPI>[FILEAPI]</a></p>

    <ul class=brief><li>The <dfn id=blob><a href=https://w3c.github.io/FileAPI/#dfn-Blob><code>Blob</code></a></dfn> interface and its
             <dfn id=dom-blob-type><a href=https://w3c.github.io/FileAPI/#dfn-type><code>type</code></a></dfn> attribute<li>The <dfn id=file><a href=https://w3c.github.io/FileAPI/#dfn-file><code>File</code></a></dfn> interface and its
             <dfn id=dom-file-name><a href=https://w3c.github.io/FileAPI/#dfn-name><code>name</code></a></dfn> and
             <dfn id=dom-file-lastmodified><a href=https://w3c.github.io/FileAPI/#dfn-lastModified><code>lastModified</code></a></dfn> attributes<li>The <dfn id=filelist><a href=https://w3c.github.io/FileAPI/#filelist-section><code>FileList</code></a></dfn> interface<li>The concept of a <code id=dependencies:blob><a data-x-internal=blob href=https://w3c.github.io/FileAPI/#dfn-Blob>Blob</a></code>'s <dfn id=snapshot-state><a href=https://w3c.github.io/FileAPI/#snapshot-state>snapshot state</a></dfn><li>The concept of <dfn id=file-error-read>read errors</dfn><li><dfn id=blob-url-store><a href=https://w3c.github.io/FileAPI/#BlobURLStore>Blob URL Store</a></dfn><li><dfn id=blob-url-entry><a href=https://w3c.github.io/FileAPI/#blob-url-entry>blob URL entry</a></dfn> and its
         <dfn id=blob-url-entry-environment><a href=https://w3c.github.io/FileAPI/#blob-url-entry-environment>environment</a></dfn><li>The <dfn id=blob-url-obtain-object><a href=https://w3c.github.io/FileAPI/#blob-url-obtain-object>obtain a blob object</a></dfn> algorithm</ul>
   <dt>Indexed Database API<dd>
    <p>The following terms are defined in <cite>Indexed Database API</cite>:
    <a href=references.html#refsINDEXEDDB>[INDEXEDDB]</a></p>

    <ul class=brief><li><dfn id=cleanup-indexed-database-transactions><a href=https://w3c.github.io/IndexedDB/#cleanup-indexed-database-transactions>cleanup Indexed Database transactions</a></dfn><li><dfn id=idbversionchangeevent><a href=https://w3c.github.io/IndexedDB/#idbversionchangeevent><code>IDBVersionChangeEvent</code></a></dfn></ul>
   <dt>Media Source Extensions<dd>
    <p>The following terms are defined in <cite>Media Source Extensions</cite>:
    <a href=references.html#refsMEDIASOURCE>[MEDIASOURCE]</a></p>

    <ul class=brief><li><dfn id=mediasource><a href=https://w3c.github.io/media-source/#idl-def-mediasource><code>MediaSource</code></a></dfn> interface<li><dfn id=detaching-from-a-media-element><a href=https://w3c.github.io/media-source/#mediasource-detach>detaching from a media element</a></dfn></ul>
   <dt>Media Capture and Streams<dd>
    <p>The following terms are defined in <cite>Media Capture and Streams</cite>:
    <a href=references.html#refsMEDIASTREAM>[MEDIASTREAM]</a></p>

    <ul class=brief><li><dfn id=mediastream><a href=https://w3c.github.io/mediacapture-main/getusermedia.html#idl-def-mediastream><code>MediaStream</code></a></dfn> interface<li><dfn id=mediastreamtrack><a href=https://w3c.github.io/mediacapture-main/getusermedia.html#mediastreamtrack><code>MediaStreamTrack</code></a></dfn><li><dfn id=live-state><a href=https://w3c.github.io/mediacapture-main/getusermedia.html#idl-def-MediaStreamTrackState.live>live state</a></dfn><li><dfn id=getusermedia()><a href=https://w3c.github.io/mediacapture-main/getusermedia.html#dom-mediadevices-getusermedia><code>getUserMedia()</code></a></dfn></ul>
   <dt>Reporting<dd>
    <p>The following terms are defined in <cite>Reporting</cite>: <a href=references.html#refsREPORTING>[REPORTING]</a></p>

    <ul class=brief><li><dfn id=queue-a-report><a href=https://w3c.github.io/reporting/#queue-report>Queue a report</a></dfn><li><dfn id=report-type><a href=https://w3c.github.io/reporting/#report-type>report type</a></dfn><li><dfn id=visible-to-reportingobservers><a href=https://w3c.github.io/reporting/#visible-to-reportingobservers>visible to <code>ReportingObserver</code>s</a></dfn></ul>
   <dt>XMLHttpRequest<dd>
    <p>The following features and terms are defined in <cite>XMLHttpRequest</cite>:
    <a href=references.html#refsXHR>[XHR]</a></p>

    <ul class=brief><li>The <dfn id=xmlhttprequest><a href=https://xhr.spec.whatwg.org/#xmlhttprequest><code>XMLHttpRequest</code></a></dfn> interface, and its
             <dfn id=dom-xmlhttprequest-responsexml><a href=https://xhr.spec.whatwg.org/#dom-xmlhttprequest-responsexml><code>responseXML</code></a></dfn> attribute<li>The <dfn id=progressevent><a href=https://xhr.spec.whatwg.org/#interface-progressevent><code>ProgressEvent</code></a></dfn> interface, and its
             <dfn id=dom-progressevent-lengthcomputable><a href=https://xhr.spec.whatwg.org/#dom-progressevent-lengthcomputable><code>lengthComputable</code></a></dfn>,
             <dfn id=dom-progressevent-loaded><a href=https://xhr.spec.whatwg.org/#dom-progressevent-loaded><code>loaded</code></a></dfn>, and
             <dfn id=dom-progressevent-total><a href=https://xhr.spec.whatwg.org/#dom-progressevent-total><code>total</code></a></dfn> attributes<li>The <dfn id=formdata><a href=https://xhr.spec.whatwg.org/#formdata><code>FormData</code></a></dfn> interface, and its associated
             <dfn id=formdata-entry-list><a href=https://xhr.spec.whatwg.org/#concept-formdata-entry-list>entry list</a></dfn></ul>
   <dt>Battery Status<dd>
    <p>The following features are defined in <cite>Battery Status API</cite>: <a href=references.html#refsBATTERY>[BATTERY]</a></p>

    <ul class=brief><li><dfn id=dom-navigator-getbattery><a href=https://w3c.github.io/battery/#widl-Navigator-getBattery-Promise-BatteryManager><code>getBattery()</code></a></dfn> method</ul>
   <dt>Media Queries<dd>
    <p>Implementations must support <cite>Media Queries</cite>. The <dfn id=media-condition><a href=https://drafts.csswg.org/mediaqueries/#typedef-media-condition>&lt;media-condition></a></dfn>
    feature is defined therein. <a href=references.html#refsMQ>[MQ]</a></p>
   <dt>CSS modules<dd>
    <p>While support for CSS as a whole is not required of implementations of this specification
    (though it is encouraged, at least for web browsers), some features are defined in terms of
    specific CSS requirements.</p>

    <p>When this specification requires that something be <dfn id=parse-something-according-to-a-css-grammar><a href=https://drafts.csswg.org/css-syntax/#parse-grammar>parsed according
    to a particular CSS grammar</a></dfn>, the relevant algorithm in <cite>CSS Syntax</cite> must be
    followed, including error handling rules. <a href=references.html#refsCSSSYNTAX>[CSSSYNTAX]</a></p>

    <p class=example>For example, user agents are required to close all open constructs upon
    finding the end of a style sheet unexpectedly. Thus, when parsing the string "<code>rgb(0,0,0</code>" (with a missing close-parenthesis) for a color value, the close
    parenthesis is implied by this error handling rule, and a value is obtained (the color 'black').
    However, the similar construct "<code>rgb(0,0,</code>" (with both a missing
    parenthesis and a missing "blue" value) cannot be parsed, as closing the open construct does not
    result in a viable value.</p>

    <p>The following terms and features are defined in <cite>Cascading Style Sheets</cite>
    (<cite>CSS</cite>): <a href=references.html#refsCSS>[CSS]</a></p>

    <ul class=brief><li><dfn id=viewport><a href=https://drafts.csswg.org/css2/#viewport>viewport</a></dfn><li><dfn id=line-box><a href=https://drafts.csswg.org/css2/#line-box>line box</a></dfn><li><dfn id=out-of-flow><a href=https://drafts.csswg.org/css2/#out-of-flow>out-of-flow</a></dfn><li><dfn id=in-flow><a href=https://drafts.csswg.org/css2/#in-flow>in-flow</a></dfn><li><dfn id=collapsing-margins><a href=https://drafts.csswg.org/css2/#collapsing-margins>collapsing margins</a></dfn><li><dfn id=containing-block><a href=https://drafts.csswg.org/css2/#containing-block-details>containing block</a></dfn><li><dfn id=inline-box><a href=https://drafts.csswg.org/css2/#inline-box>inline box</a></dfn><li><dfn id=block-box><a href=https://drafts.csswg.org/css2/#block-boxes%E2%91%A0>block box</a></dfn><li>The <dfn id="'top'"><a href=https://drafts.csswg.org/css2/#propdef-top>'top'</a></dfn>,
              <dfn id="'bottom'"><a href=https://drafts.csswg.org/css2/#propdef-bottom>'bottom'</a></dfn>,
              <dfn id="'left'"><a href=https://drafts.csswg.org/css2/#propdef-left>'left'</a></dfn>, and
              <dfn id="'right'"><a href=https://drafts.csswg.org/css2/#propdef-right>'right'</a></dfn> properties<li>The <dfn id="'float'"><a href=https://drafts.csswg.org/css2/#float-position>'float'</a></dfn> property<li>The <dfn id="'clear'"><a href=https://drafts.csswg.org/css2/#flow-control>'clear'</a></dfn> property<li>The <dfn id="'width'"><a href=https://drafts.csswg.org/css2/#the-width-property>'width'</a></dfn> property<li>The <dfn id="'height'"><a href=https://drafts.csswg.org/css2/#the-height-property>'height'</a></dfn> property<li>The <dfn id="'min-width'"><a href=https://drafts.csswg.org/css2/#min-max-widths>'min-width'</a></dfn> property<li>The <dfn id="'min-height'"><a href=https://drafts.csswg.org/css2/#min-max-heights>'min-height'</a></dfn> property<li>The <dfn id="'max-width'"><a href=https://drafts.csswg.org/css2/#min-max-widths>'max-width'</a></dfn> property<li>The <dfn id="'max-height'"><a href=https://drafts.csswg.org/css2/#min-max-heights>'max-height'</a></dfn> property<li>The <dfn id="'line-height'"><a href=https://drafts.csswg.org/css2/#propdef-line-height>'line-height'</a></dfn> property<li>The <dfn id="'vertical-align'"><a href=https://drafts.csswg.org/css2/#propdef-vertical-align>'vertical-align'</a></dfn> property<li>The <dfn id="'content'"><a href=https://drafts.csswg.org/css2/#content%E2%91%A0>'content'</a></dfn> property<li>The <dfn id="'inline-block'"><a href=https://drafts.csswg.org/css2/#value-def-inline-block>'inline-block'</a></dfn> value of the <a id="dependencies:'display'" href=https://drafts.csswg.org/css2/#display-prop data-x-internal="'display'">'display'</a> property<li>The <dfn id="'visibility'"><a href=https://drafts.csswg.org/css2/#propdef-visibility>'visibility'</a></dfn> property</ul>

    <p>The basic version of the <dfn id="'display'"><a href=https://drafts.csswg.org/css2/#display-prop>'display'</a></dfn> property
    is defined in <cite>CSS</cite>, and the property is extended by other CSS modules.
    <a href=references.html#refsCSS>[CSS]</a> <a href=references.html#refsCSSRUBY>[CSSRUBY]</a> <a href=references.html#refsCSSTABLE>[CSSTABLE]</a></p>

    <p>The following terms and features are defined in <cite>CSS Box Model</cite>:
    <a href=references.html#refsCSSBOX>[CSSBOX]</a></p>

    <ul><li><dfn id=content-area><a href=https://drafts.csswg.org/css-box/#content-area>content area</a></dfn><li><dfn id=content-box><a href=https://drafts.csswg.org/css-box/#content-box>content box</a></dfn><li><dfn id=border-box><a href=https://drafts.csswg.org/css-box/#border-box>border box</a></dfn><li><dfn id=margin-box><a href=https://drafts.csswg.org/css-box/#margin-box>margin box</a></dfn><li><dfn id=border-edge><a href=https://drafts.csswg.org/css-box/#border-edge>border edge</a></dfn><li><dfn id=margin-edge><a href=https://drafts.csswg.org/css-box/#margin-edge>margin edge</a></dfn><li>The <dfn id="'margin-top'"><a href=https://drafts.csswg.org/css-box/#propdef-margin-top>'margin-top'</a></dfn>,
              <dfn id="'margin-bottom'"><a href=https://drafts.csswg.org/css-box/#propdef-margin-bottom>'margin-bottom'</a></dfn>,
              <dfn id="'margin-left'"><a href=https://drafts.csswg.org/css-box/#propdef-margin-left>'margin-left'</a></dfn>, and
              <dfn id="'margin-right'"><a href=https://drafts.csswg.org/css-box/#propdef-margin-right>'margin-right'</a></dfn> properties<li>The <dfn id="'padding-top'"><a href=https://drafts.csswg.org/css-box/#propdef-padding-top>'padding-top'</a></dfn>,
              <dfn id="'padding-bottom'"><a href=https://drafts.csswg.org/css-box/#propdef-padding-bottom>'padding-bottom'</a></dfn>,
              <dfn id="'padding-left'"><a href=https://drafts.csswg.org/css-box/#propdef-padding-left>'padding-left'</a></dfn>, and
              <dfn id="'padding-right'"><a href=https://drafts.csswg.org/css-box/#propdef-padding-right>'padding-right'</a></dfn> properties</ul>

    <p>The following features are defined in <cite>CSS Logical Properties</cite>:
    <a href=references.html#refsCSSLOGICAL>[CSSLOGICAL]</a></p>

    <ul class=brief><li>The <dfn id="'margin-block'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-block>'margin-block'</a></dfn>,
              <dfn id="'margin-block-start'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-block-start>'margin-block-start'</a></dfn>,
              <dfn id="'margin-block-end'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-block-end>'margin-block-end'</a></dfn>,
              <dfn id="'margin-inline'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-inline>'margin-inline'</a></dfn>,
              <dfn id="'margin-inline-start'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-inline-start>'margin-inline-start'</a></dfn>, and
              <dfn id="'margin-inline-end'"><a href=https://drafts.csswg.org/css-logical/#propdef-margin-inline-end>'margin-inline-end'</a></dfn> properties<li>The <dfn id="'padding-block'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-block>'padding-block'</a></dfn>,
              <dfn id="'padding-block-start'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-block-start>'padding-block-start'</a></dfn>,
              <dfn id="'padding-block-end'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-block-end>'padding-block-end'</a></dfn>,
              <dfn id="'padding-inline'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-inline>'padding-inline'</a></dfn>,
              <dfn id="'padding-inline-start'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-inline-start>'padding-inline-start'</a></dfn>, and
              <dfn id="'padding-inline-end'"><a href=https://drafts.csswg.org/css-logical/#propdef-padding-inline-end>'padding-inline-end'</a></dfn> properties<li>The <dfn id="'border-block-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-width>'border-block-width'</a></dfn>,
              <dfn id="'border-block-start-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-start-width>'border-block-start-width'</a></dfn>,
              <dfn id="'border-block-end-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-end-width>'border-block-end-width'</a></dfn>,
              <dfn id="'border-inline-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-width>'border-inline-width'</a></dfn>,
              <dfn id="'border-inline-start-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-start-width>'border-inline-start-width'</a></dfn>,
              <dfn id="'border-inline-end-width'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-end-width>'border-inline-end-width'</a></dfn>,
              <dfn id="'border-block-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-style>'border-block-style'</a></dfn>,
              <dfn id="'border-block-start-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-start-style>'border-block-start-style'</a></dfn>,
              <dfn id="'border-block-end-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-end-style>'border-block-end-style'</a></dfn>,
              <dfn id="'border-inline-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-style>'border-inline-style'</a></dfn>,
              <dfn id="'border-inline-start-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-start-style>'border-inline-start-style'</a></dfn>,
              <dfn id="'border-inline-end-style'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-end-style>'border-inline-end-style'</a></dfn>,
              <dfn id="'border-block-start-color'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-start-color>'border-block-start-color'</a></dfn>,
              <dfn id="'border-block-end-color'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-block-end-color>'border-block-end-color'</a></dfn>,
              <dfn id="'border-inline-start-color'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-start-color>'border-inline-start-color'</a></dfn>,
              <dfn id="'border-inline-end-color'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-inline-end-color>'border-inline-end-color'</a></dfn>,
              <dfn id="'border-start-start-radius'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-start-start-radius>'border-start-start-radius'</a></dfn>,
              <dfn id="'border-start-end-radius'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-start-end-radius>'border-start-end-radius'</a></dfn>,
              <dfn id="'border-end-start-radius'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-end-start-radius>'border-end-start-radius'</a></dfn>, and
              <dfn id="'border-end-end-radius'"><a href=https://drafts.csswg.org/css-logical/#propdef-border-end-end-radius>'border-end-end-radius'</a></dfn>
              properties<li>The <dfn id="'block-size'"><a href=https://drafts.csswg.org/css-logical/#propdef-block-size>'block-size'</a></dfn> property<li>The <dfn id="'inline-size'"><a href=https://drafts.csswg.org/css-logical/#propdef-inline-size>'inline-size'</a></dfn> property<li>The <dfn id="'inset-block-start'"><a href=https://drafts.csswg.org/css-logical/#propdef-inset-block-start>'inset-block-start'</a></dfn> property<li>The <dfn id="'inset-block-end'"><a href=https://drafts.csswg.org/css-logical/#propdef-inset-block-end>'inset-block-end'</a></dfn> property</ul>

    <p>The following terms and features are defined in <cite>CSS Color</cite>:
    <a href=references.html#refsCSSCOLOR>[CSSCOLOR]</a></p>

    <ul class=brief><li><dfn id=named-color><a href=https://drafts.csswg.org/css-color/#named-color>named color</a></dfn><li><dfn id=color><a href=https://drafts.csswg.org/css-color/#typedef-color>&lt;color></a></dfn><li>The <dfn id="'color'"><a href=https://drafts.csswg.org/css-color/#the-color-property>'color'</a></dfn> property<li>The <dfn id=currentcolor><a href=https://drafts.csswg.org/css-color/#valdef-color-currentcolor>'currentcolor'</a></dfn> value<li><dfn id=opaque-black><a href=https://drafts.csswg.org/css-color/#opaque-black>opaque black</a></dfn><li><dfn id=transparent-black><a href=https://drafts.csswg.org/css-color/#transparent-black>transparent black</a></dfn><li><dfn id="'srgb'"><a href=https://drafts.csswg.org/css-color/#valdef-color-srgb>'srgb'</a></dfn> color space<li><dfn id="'display-p3'"><a href=https://drafts.csswg.org/css-color/#valdef-color-display-p3>'display-p3'</a></dfn> color space<li><dfn id="'relative-colorimetric'"><a href=https://drafts.csswg.org/css-color-5/#valdef-color-profile-rendering-intent-relative-colorimetric>'relative-colorimetric'</a></dfn> rendering intent<li><dfn id=parsed-as-a-css-color-value><a href=https://drafts.csswg.org/css-color/#parse-a-css-color-value>parse a CSS &lt;color> value</a></dfn><li><dfn id=serialisation-of-a-color><a href=https://drafts.csswg.org/css-color/#serializing-color-values>serialize a CSS &lt;color> value</a></dfn> including <dfn id=html-compatible-serialization-is-requested><a href=https://drafts.csswg.org/css-color/#color-serialization-html-compatible-serialization-is-requested>HTML-compatible serialization is requested</a></dfn><li><dfn id=converting-colors><a href=https://drafts.csswg.org/css-color/#color-conversion>Converting Colors</a></dfn><li><dfn id=color-function><a href=https://drafts.csswg.org/css-color/#color-function>'color()'</a></dfn></ul>

    <p>The following terms are defined in <cite>CSS Images</cite>: <a href=references.html#refsCSSIMAGES>[CSSIMAGES]</a></p>

    <ul class=brief><li><dfn id=default-object-size><a href=https://drafts.csswg.org/css-images/#default-object-size>default object size</a></dfn><li><dfn id=concrete-object-size><a href=https://drafts.csswg.org/css-images/#concrete-object-size>concrete object size</a></dfn><li><dfn id=natural-dimensions><a href=https://drafts.csswg.org/css-images/#natural-dimensions>natural dimensions</a></dfn><li><dfn id=natural-height><a href=https://drafts.csswg.org/css-images/#natural-height>natural height</a></dfn><li><dfn id=natural-width><a href=https://drafts.csswg.org/css-images/#natural-width>natural width</a></dfn><li>The <dfn id="'image-orientation'"><a href=https://drafts.csswg.org/css-images-3/#the-image-orientation>'image-orientation'</a></dfn> property<li><dfn id="'conic-gradient'"><a href=https://drafts.csswg.org/css-images-4/#funcdef-conic-gradient>'conic-gradient'</a></dfn><li>The <dfn id="'object-fit'"><a href=https://drafts.csswg.org/css-images/#the-object-fit>'object-fit'</a></dfn> property</ul>

    <p>The term <dfn id=paint-source><a href=https://drafts.csswg.org/css-images-4/#paint-source>paint
    source</a></dfn> is used as defined in <cite>CSS Images Level 4</cite>
    to define the interaction of certain HTML elements with the CSS 'element()' function.
    <a href=references.html#refsCSSIMAGES4>[CSSIMAGES4]</a></p>

    <p>The following features are defined in <cite>CSS Backgrounds and Borders</cite>:
    <a href=references.html#refsCSSBG>[CSSBG]</a></p>

    <ul class=brief><li>The <dfn id="'background-color'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-color>'background-color'</a></dfn>,
              <dfn id="'background-image'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-image>'background-image'</a></dfn>,
              <dfn id="'background-repeat'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-repeat>'background-repeat'</a></dfn>,
              <dfn id="'background-attachment'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-attachment>'background-attachment'</a></dfn>,
              <dfn id="'background-position'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-position>'background-position'</a></dfn>,
              <dfn id="'background-clip'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-clip>'background-clip'</a></dfn>,
              <dfn id="'background-origin'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-origin>'background-origin'</a></dfn>, and
              <dfn id="'background-size'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-background-size>'background-size'</a></dfn>
              properties<li>The <dfn id="'border-radius'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-radius>'border-radius'</a></dfn>,
              <dfn id="'border-top-left-radius'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-top-left-radius>'border-top-left-radius'</a></dfn>,
              <dfn id="'border-top-right-radius'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-top-right-radius>'border-top-right-radius'</a></dfn>,
              <dfn id="'border-bottom-right-radius'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-bottom-right-radius>'border-bottom-right-radius'</a></dfn>,
              <dfn id="'border-bottom-left-radius'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-bottom-left-radius>'border-bottom-left-radius'</a></dfn>
              properties<li>The <dfn id="'border-image-source'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-image-source>'border-image-source'</a></dfn>,
              <dfn id="'border-image-slice'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-image-slice>'border-image-slice'</a></dfn>,
              <dfn id="'border-image-width'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-image-width>'border-image-width'</a></dfn>,
              <dfn id="'border-image-outset'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-image-outset>'border-image-outset'</a></dfn>, and
              <dfn id="'border-image-repeat'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-image-repeat>'border-image-repeat'</a></dfn>
              properties</ul>

    <p><cite>CSS Backgrounds and Borders</cite> also defines the following border properties:
    <a href=references.html#refsCSSBG>[CSSBG]</a></p>

    <table><caption>Border properties
     </caption><tr><td>
       <th>Top
       <th>Bottom
       <th>Left
       <th>Right
      <tr><th>Width
       <td><dfn id="'border-top-width'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-top-width>'border-top-width'</a></dfn>
       <td><dfn id="'border-bottom-width'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-bottom-width>'border-bottom-width'</a></dfn>
       <td><dfn id="'border-left-width'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-left-width>'border-left-width'</a></dfn>
       <td><dfn id="'border-right-width'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-right-width>'border-right-width'</a></dfn>
      <tr><th>Style
       <td><dfn id="'border-top-style'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-top-style>'border-top-style'</a></dfn>
       <td><dfn id="'border-bottom-style'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-bottom-style>'border-bottom-style'</a></dfn>
       <td><dfn id="'border-left-style'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-left-style>'border-left-style'</a></dfn>
       <td><dfn id="'border-right-style'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-right-style>'border-right-style'</a></dfn>
      <tr><th>Color
       <td><dfn id="'border-top-color'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-top-color>'border-top-color'</a></dfn>
       <td><dfn id="'border-bottom-color'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-bottom-color>'border-bottom-color'</a></dfn>
       <td><dfn id="'border-left-color'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-left-color>'border-left-color'</a></dfn>
       <td><dfn id="'border-right-color'"><a href=https://drafts.csswg.org/css-backgrounds/#propdef-border-right-color>'border-right-color'</a></dfn>
    </table>

    <p>The following features are defined in <cite>CSS Box Alignment</cite>: <a href=references.html#refsCSSALIGN>[CSSALIGN]</a></p>

    <ul class=brief><li>The <dfn id="'align-content'"><a href=https://drafts.csswg.org/css-align/#propdef-align-content>'align-content'</a></dfn> property<li>The <dfn id="'align-items'"><a href=https://drafts.csswg.org/css-align/#propdef-align-items>'align-items'</a></dfn> property<li>The <dfn id="'align-self'"><a href=https://drafts.csswg.org/css-align/#propdef-align-self>'align-self'</a></dfn> property<li>The <dfn id="'justify-self'"><a href=https://drafts.csswg.org/css-align/#propdef-justify-self>'justify-self'</a></dfn> property<li>The <dfn id="'justify-content'"><a href=https://drafts.csswg.org/css-align/#propdef-propdef-justify-content>'justify-content'</a></dfn> property<li>The <dfn id="'justify-items'"><a href=https://drafts.csswg.org/css-align/#propdef-propdef-justify-items>'justify-items'</a></dfn> property</ul>

    <p>The following terms and features are defined in <cite>CSS Display</cite>:
    <a href=references.html#refsCSSDISPLAY>[CSSDISPLAY]</a></p>

    <ul class=brief><li><dfn id=outer-display-type><a href=https://drafts.csswg.org/css-display/#outer-display-type>outer display type</a></dfn><li><dfn id=inner-display-type><a href=https://drafts.csswg.org/css-display/#inner-display-type>inner display type</a></dfn><li><dfn id=block-level><a href=https://drafts.csswg.org/css-display/#block-level>block-level</a></dfn><li><dfn id=block-container><a href=https://drafts.csswg.org/css-display/#block-container>block container</a></dfn><li><dfn id=formatting-context><a href=https://drafts.csswg.org/css-display/#formatting-context>formatting context</a></dfn><li><dfn id=block-formatting-context><a href=https://drafts.csswg.org/css-display/#block-formatting-context>block formatting context</a></dfn><li><dfn id=inline-formatting-context><a href=https://drafts.csswg.org/css-display/#inline-formatting-context>inline formatting context</a></dfn><li><dfn id=replaced-element><a href=https://drafts.csswg.org/css-display/#replaced-element>replaced element</a></dfn><li><dfn id=css-box><a href=https://drafts.csswg.org/css-display/#css-box>CSS box</a></dfn></ul>

    <p>The following features are defined in <cite>CSS Flexible Box Layout</cite>:
    <a href=references.html#refsCSSFLEXBOX>[CSSFLEXBOX]</a></p>

    <ul class=brief><li>The <dfn id="'flex-direction'"><a href=https://drafts.csswg.org/css-flexbox/#propdef-flex-direction>'flex-direction'</a></dfn> property<li>The <dfn id="'flex-wrap'"><a href=https://drafts.csswg.org/css-flexbox/#propdef-flex-wrap>'flex-wrap'</a></dfn> property</ul>

    <p>The following terms and features are defined in <cite>CSS Fonts</cite>:
    <a href=references.html#refsCSSFONTS>[CSSFONTS]</a></p>

    <ul class=brief><li><dfn id=first-available-font><a href=https://drafts.csswg.org/css-fonts/#first-available-font>first available font</a></dfn><li>The <dfn id="'font-family'"><a href=https://drafts.csswg.org/css-fonts/#font-family-prop>'font-family'</a></dfn> property<li>The <dfn id="'font-weight'"><a href=https://drafts.csswg.org/css-fonts/#font-weight-prop>'font-weight'</a></dfn> property<li>The <dfn id="'font-size'"><a href=https://drafts.csswg.org/css-fonts/#font-size-prop>'font-size'</a></dfn> property<li>The <dfn id="'font'"><a href=https://drafts.csswg.org/css-fonts/#font-prop>'font'</a></dfn> property<li>The <dfn id="'font-kerning'"><a href=https://drafts.csswg.org/css-fonts/#propdef-font-kerning>'font-kerning'</a></dfn> property<li>The <dfn id="'font-stretch'"><a href=https://drafts.csswg.org/css-fonts/#propdef-font-stretch>'font-stretch'</a></dfn> property<li>The <dfn id="'font-variant-caps'"><a href=https://drafts.csswg.org/css-fonts/#propdef-font-variant-caps>'font-variant-caps'</a></dfn> property<li>The <dfn id="'small-caps'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-small-caps>'small-caps'</a></dfn> value<li>The <dfn id="'all-small-caps'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-all-small-caps>'all-small-caps'</a></dfn> value<li>The <dfn id="'petite-caps'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-petite-caps>'petite-caps'</a></dfn> value<li>The <dfn id="'all-petite-caps'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-all-petite-caps>'all-petite-caps'</a></dfn> value<li>The <dfn id="'unicase'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-unicase>'unicase'</a></dfn> value<li>The <dfn id="'titling-caps'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-variant-caps-titling-caps>'titling-caps'</a></dfn> value<li>The <dfn id="'ultra-condensed'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-ultra-condensed>'ultra-condensed'</a></dfn> value<li>The <dfn id="'extra-condensed'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-extra-condensed>'extra-condensed'</a></dfn> value<li>The <dfn id="'condensed'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-condensed>'condensed'</a></dfn> value<li>The <dfn id="'semi-condensed'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-semi-condensed>'semi-condensed'</a></dfn> value<li>The <dfn id="'semi-expanded'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-semi-expanded>'semi-expanded'</a></dfn> value<li>The <dfn id="'expanded'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-expanded>'expanded'</a></dfn> value<li>The <dfn id="'extra-expanded'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-extra-expanded>'extra-expanded'</a></dfn> value<li>The <dfn id="'ultra-expanded'"><a href=https://drafts.csswg.org/css-fonts/#valdef-font-stretch-ultra-expanded>'ultra-expanded'</a></dfn> value</ul>

    <p>The following features are defined in <cite>CSS Forms</cite>:
    <a href=references.html#refsCSSFORMS>[CSSFORMS]</a></p>

    <ul class=brief><li><dfn id="'::picker'"><a href=https://drafts.csswg.org/css-forms/#the-picker-pseudo-element>'::picker'</a></dfn><li><dfn id="'::checkmark'"><a href=https://drafts.csswg.org/css-forms/#selectordef-checkmark>'::checkmark'</a></dfn><li><dfn id="'::picker-icon'"><a href=https://drafts.csswg.org/css-forms/#picker-opener-icon-the-picker-icon-pseudo-element>'::picker-icon'</a></dfn></ul>

    <p>The following features are defined in <cite>CSS Grid Layout</cite>: <a href=references.html#refsCSSGRID>[CSSGRID]</a></p>

    <ul class=brief><li>The <dfn id="'grid-auto-columns'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-auto-columns>'grid-auto-columns'</a></dfn> property<li>The <dfn id="'grid-auto-flow'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-auto-flow>'grid-auto-flow'</a></dfn> property<li>The <dfn id="'grid-auto-rows'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-auto-rows>'grid-auto-rows'</a></dfn> property<li>The <dfn id="'grid-column-gap'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-column-gap>'grid-column-gap'</a></dfn> property<li>The <dfn id="'grid-row-gap'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-row-gap>'grid-row-gap'</a></dfn> property<li>The <dfn id="'grid-template-areas'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-template-areas>'grid-template-areas'</a></dfn> property<li>The <dfn id="'grid-template-columns'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-template-columns>'grid-template-columns'</a></dfn> property<li>The <dfn id="'grid-template-rows'"><a href=https://drafts.csswg.org/css-grid/#propdef-grid-template-rows>'grid-template-rows'</a></dfn> property</ul>

    <p>The following terms are defined in <cite>CSS Inline Layout</cite>: <a href=references.html#refsCSSINLINE>[CSSINLINE]</a></p>

    <ul class=brief><li><dfn id=alphabetic-baseline><a href=https://drafts.csswg.org/css-inline/#alphabetic-baseline>alphabetic baseline</a></dfn><li><dfn id=ascent-metric><a href=https://drafts.csswg.org/css-inline/#ascent-metric>ascent metric</a></dfn><li><dfn id=descent-metric><a href=https://drafts.csswg.org/css-inline/#descent-metric>descent metric</a></dfn><li><dfn id=em-over-baseline><a href=https://drafts.csswg.org/css-inline/#em-over-baseline>em-over baseline</a></dfn><li><dfn id=em-under-baseline><a href=https://drafts.csswg.org/css-inline/#em-under-baseline>em-under baseline</a></dfn><li><dfn id=hanging-baseline><a href=https://drafts.csswg.org/css-inline/#hanging-baseline>hanging baseline</a></dfn><li><dfn id=ideographic-under-baseline><a href=https://drafts.csswg.org/css-inline/#ideographic-under-baseline>ideographic-under baseline</a></dfn></ul>

    <p>The following terms and features are defined in <cite>CSS Box Sizing</cite>:
    <a href=references.html#refsCSSSIZING>[CSSSIZING]</a></p>

    <ul class=brief><li><dfn id=fit-content-inline-size><a href=https://drafts.csswg.org/css-sizing/#fit-content-inline-size>fit-content inline size</a></dfn><li><dfn id="'aspect-ratio'"><a href=https://drafts.csswg.org/css-sizing-4/#aspect-ratio>'aspect-ratio'</a></dfn> property<li><dfn id=intrinsic-size><a href=https://drafts.csswg.org/css-sizing/#intrinsic-size>intrinsic size</a></dfn></ul>

    <p>The following features are defined in <cite>CSS Lists and Counters</cite>.
    <a href=references.html#refsCSSLISTS>[CSSLISTS]</a></p>

    <ul class=brief><li><dfn id=css-list-item><a href=https://drafts.csswg.org/css-lists/#list-item>list item</a></dfn><li>The <dfn id="'counter-reset'"><a href=https://drafts.csswg.org/css-lists/#propdef-counter-reset>'counter-reset'</a></dfn> property<li>The <dfn id="'counter-set'"><a href=https://drafts.csswg.org/css-lists/#propdef-counter-set>'counter-set'</a></dfn> property<li>The <dfn id="'list-style-type'"><a href=https://drafts.csswg.org/css-lists/#propdef-list-style-type>'list-style-type'</a></dfn> property</ul>

    <p>The following features are defined in <cite>CSS Overflow</cite>. <a href=references.html#refsCSSOVERFLOW>[CSSOVERFLOW]</a></p>

    <ul class=brief><li>The <dfn id="'overflow'"><a href=https://drafts.csswg.org/css-overflow/#propdef-overflow>'overflow'</a></dfn> property and its <dfn id="'hidden'"><a href=https://drafts.csswg.org/css-overflow/#valdef-overflow-hidden>'hidden'</a></dfn> value<li>The <dfn id="'text-overflow'"><a href=https://drafts.csswg.org/css-overflow/#propdef-text-overflow>'text-overflow'</a></dfn> property<li>The term <dfn id=scroll-container><a href=https://drafts.csswg.org/css-overflow/#scroll-container>scroll container</a></dfn>
    </ul>

    <p>The following terms and features are defined in <cite>CSS Positioned Layout</cite>:
    <a href=references.html#refsCSSPOSITION>[CSSPOSITION]</a></p>

    <ul class=brief><li><dfn id=absolutely-positioned><a href=https://drafts.csswg.org/css-position/#absolute-position>absolutely-positioned</a></dfn><li>The <dfn id="'position'"><a href=https://drafts.csswg.org/css-position/#position-property>'position'</a></dfn> property and its
              <dfn id="'static'"><a href=https://drafts.csswg.org/css-position/#valdef-position-static>'static'</a></dfn> value<li>The <dfn id=top-layer><a href=https://drafts.csswg.org/css-position-4/#document-top-layer>top layer</a></dfn>
              (an <a href=https://infra.spec.whatwg.org/#ordered-set id=dependencies:set data-x-internal=set>ordered set</a>)<li><dfn id=add-an-element-to-the-top-layer><a href=https://drafts.csswg.org/css-position-4/#add-an-element-to-the-top-layer>add an element to the top layer</a></dfn><li><dfn id=request-an-element-to-be-removed-from-the-top-layer><a href=https://drafts.csswg.org/css-position-4/#request-an-element-to-be-removed-from-the-top-layer>request an element to be removed from the top layer</a></dfn><li><dfn id=remove-an-element-from-the-top-layer-immediately><a href=https://drafts.csswg.org/css-position-4/#remove-an-element-from-the-top-layer-immediately>remove an element from the top layer immediately</a></dfn><li><dfn id=process-top-layer-removals><a href=https://drafts.csswg.org/css-position-4/#process-top-layer-removals>process top layer removals</a></dfn></ul>

    <p>The following features are defined in <cite>CSS Multi-column Layout</cite>.
    <a href=references.html#refsCSSMULTICOL>[CSSMULTICOL]</a></p>

    <ul class=brief><li>The <dfn id="'column-count'"><a href=https://drafts.csswg.org/css-multicol/#propdef-column-count>'column-count'</a></dfn> property<li>The <dfn id="'column-fill'"><a href=https://drafts.csswg.org/css-multicol/#propdef-column-fill>'column-fill'</a></dfn> property<li>The <dfn id="'column-gap'"><a href=https://drafts.csswg.org/css-multicol/#propdef-column-gap>'column-gap'</a></dfn> property<li>The <dfn id="'column-rule'"><a href=https://drafts.csswg.org/css-multicol/#propdef-column-rule>'column-rule'</a></dfn> property<li>The <dfn id="'column-width'"><a href=https://drafts.csswg.org/css-multicol/#propdef-column-width>'column-width'</a></dfn> property</ul>

    <p>The <dfn id="'ruby-base'"><a href=https://drafts.csswg.org/css-ruby/#valdef-display-ruby-base>'ruby-base'</a></dfn>
    value of the <a id="dependencies:'display'-2" href=https://drafts.csswg.org/css2/#display-prop data-x-internal="'display'">'display'</a> property is defined in <cite>CSS Ruby Layout</cite>.
    <a href=references.html#refsCSSRUBY>[CSSRUBY]</a></p>

    <p>The following features are defined in <cite>CSS Table</cite>: <a href=references.html#refsCSSTABLE>[CSSTABLE]</a></p>

    <ul class=brief><li>The <dfn id="'border-spacing'"><a href=https://drafts.csswg.org/css-tables/#propdef-border-spacing>'border-spacing'</a></dfn> property<li>The <dfn id="'border-collapse'"><a href=https://drafts.csswg.org/css-tables/#border-collapse-property>'border-collapse'</a></dfn> property<li>The <dfn id="'table-cell'"><a href=https://drafts.csswg.org/css-tables/#table-cell>'table-cell'</a></dfn>,
              <dfn id="'table-row'"><a href=https://drafts.csswg.org/css-tables/#table-row>'table-row'</a></dfn>,
              <dfn id="'table-caption'"><a href=https://drafts.csswg.org/css-tables/#table-caption>'table-caption'</a></dfn>, and
              <dfn id="'table'"><a href=https://drafts.csswg.org/css-tables/#table>'table'</a></dfn> values of the <a id="dependencies:'display'-3" href=https://drafts.csswg.org/css2/#display-prop data-x-internal="'display'">'display'</a> property</ul>

    <p>The following features are defined in <cite>CSS Text</cite>: <a href=references.html#refsCSSTEXT>[CSSTEXT]</a></p>

    <ul class=brief><li>The <dfn id=content-language><a href=https://drafts.csswg.org/css-text-4/#content-language>content language</a></dfn> concept<li>The <dfn id="'text-transform'"><a href=https://drafts.csswg.org/css-text/#text-transform-property>'text-transform'</a></dfn> property<li>The <dfn id="'white-space'"><a href=https://drafts.csswg.org/css-text/#white-space-property>'white-space'</a></dfn> property<li>The <dfn id="'text-align'"><a href=https://drafts.csswg.org/css-text/#text-align-property>'text-align'</a></dfn> property<li>The <dfn id="'letter-spacing'"><a href=https://drafts.csswg.org/css-text/#letter-spacing-property>'letter-spacing'</a></dfn> property<li>The <dfn id="'word-spacing'"><a href=https://drafts.csswg.org/css-text/#propdef-word-spacing>'word-spacing'</a></dfn> property</ul>

    <p>The following features are defined in <cite>CSS Writing Modes</cite>: <a href=references.html#refsCSSWM>[CSSWM]</a></p>

    <ul class=brief><li>The <dfn id="'direction'"><a href=https://drafts.csswg.org/css-writing-modes/#direction>'direction'</a></dfn> property<li>The <dfn id="'unicode-bidi'"><a href=https://drafts.csswg.org/css-writing-modes/#unicode-bidi>'unicode-bidi'</a></dfn> property<li>The <dfn id="'writing-mode'"><a href=https://drafts.csswg.org/css-writing-modes/#propdef-writing-mode>'writing-mode'</a></dfn> property<li>The <dfn id=block-flow-direction><a href=https://drafts.csswg.org/css-writing-modes/#block-flow-direction>block flow direction</a></dfn>,
              <dfn id=block-axis><a href=https://drafts.csswg.org/css-writing-modes/#block-axis>block axis</a></dfn>,
              <dfn id=inline-axis><a href=https://drafts.csswg.org/css-writing-modes/#inline-axis>inline axis</a></dfn>,
              <dfn id=block-size><a href=https://drafts.csswg.org/css-writing-modes/#block-size>block size</a></dfn>,
              <dfn id=inline-size><a href=https://drafts.csswg.org/css-writing-modes/#inline-size>inline size</a></dfn>,
              <dfn id=block-start><a href=https://drafts.csswg.org/css-writing-modes/#block-start>block-start</a></dfn>,
              <dfn id=block-end><a href=https://drafts.csswg.org/css-writing-modes/#block-end>block-end</a></dfn>,
              <dfn id=inline-start><a href=https://drafts.csswg.org/css-writing-modes/#inline-start>inline-start</a></dfn>,
              <dfn id=inline-end><a href=https://drafts.csswg.org/css-writing-modes/#inline-end>inline-end</a></dfn>,
              <dfn id=line-left><a href=https://drafts.csswg.org/css-writing-modes/#line-left>line-left</a></dfn>, and
              <dfn id=line-right><a href=https://drafts.csswg.org/css-writing-modes/#line-right>line-right</a></dfn> concepts</ul>

    <p>The following features are defined in <cite>CSS Basic User Interface</cite>:
    <a href=references.html#refsCSSUI>[CSSUI]</a></p>

    <ul class=brief><li>The <dfn id="'outline'"><a href=https://drafts.csswg.org/css-ui/#outline>'outline'</a></dfn> property<li>The <dfn id="'cursor'"><a href=https://drafts.csswg.org/css-ui/#cursor>'cursor'</a></dfn> property<li>The <dfn id="'appearance'"><a href=https://drafts.csswg.org/css-ui/#appearance-switching>'appearance'</a></dfn> property, its
              <dfn id=compat-auto><a href=https://drafts.csswg.org/css-ui/#typedef-appearance-compat-auto>&lt;compat-auto></a></dfn> non-terminal value type, its
              <dfn id="'textfield'"><a href=https://drafts.csswg.org/css-ui/#valdef-appearance-textfield>'textfield'</a></dfn> value, and its
              <dfn id="'menulist-button'"><a href=https://drafts.csswg.org/css-ui/#valdef-appearance-menulist-button>'menulist-button'</a></dfn> value.<li>The <dfn id="'field-sizing'"><a href=https://drafts.csswg.org/css-ui/#field-sizing>'field-sizing'</a></dfn> property, and its
              <dfn id=field-sizing-content><a href=https://drafts.csswg.org/css-ui/#valdef-field-sizing-content>'content'</a></dfn> value.<li>The concept <dfn id=widget><a href=https://drafts.csswg.org/css-ui/#widget>widget</a></dfn><li>The concept <dfn id=native-appearance><a href=https://drafts.csswg.org/css-ui/#native-appearance>native appearance</a></dfn><li>The concept <dfn id=primitive-appearance><a href=https://drafts.csswg.org/css-ui/#primitive-appearance>primitive appearance</a></dfn><li>The concept <dfn id=base-appearance><a href=https://drafts.csswg.org/css-ui/#base-appearance>base appearance</a></dfn><li>The concept <dfn id=element-with-default-preferred-size><a href=https://drafts.csswg.org/css-ui/#element-with-default-preferred-size>element with default preferred size</a></dfn><li>The <dfn id=non-devolvable-widget><a href=https://drafts.csswg.org/css-ui/#non-devolvable>non-devolvable widget</a></dfn> and
              <dfn id=devolvable-widget><a href=https://drafts.csswg.org/css-ui/#devolvable>devolvable widget</a></dfn> classification, and the related
              <dfn id=devolved-widget><a href=https://drafts.csswg.org/css-ui/#devolved>devolved widget</a></dfn> state.<li>The <dfn id="'pointer-events'"><a href=https://drafts.csswg.org/css-ui-4/#pointer-events-control>'pointer-events'</a></dfn> property<li>The <dfn id="'user-select'"><a href=https://drafts.csswg.org/css-ui-4/#content-selection>'user-select'</a></dfn> property</ul>

    <p>The algorithm to <dfn id=update-animations-and-send-events><a href=https://drafts.csswg.org/web-animations-1/#update-animations-and-send-events>update
    animations and send events</a></dfn> is defined in <cite>Web Animations</cite>.
    <a href=references.html#refsWEBANIMATIONS>[WEBANIMATIONS]</a></p>

    <p>Implementations that support scripting must support the CSS Object Model. The following
    features and terms are defined in the CSSOM specifications: <a href=references.html#refsCSSOM>[CSSOM]</a>
    <a href=references.html#refsCSSOMVIEW>[CSSOMVIEW]</a>

    <ul class=brief><li><dfn id=screen><a href=https://drafts.csswg.org/cssom-view/#the-screen-interface><code>Screen</code></a></dfn> interface<li><dfn id=linkstyle><a href=https://drafts.csswg.org/cssom/#the-linkstyle-interface><code>LinkStyle</code></a></dfn> interface<li><dfn id=cssstyledeclaration><a href=https://drafts.csswg.org/cssom/#the-cssstyledeclaration-interface><code>CSSStyleDeclaration</code></a></dfn> interface<li><dfn id=dom-style><a href=https://drafts.csswg.org/cssom/#dom-elementcssinlinestyle-style><code>style</code></a></dfn> IDL attribute<li><dfn id=dom-cssstyledeclaration-csstext><a href=https://drafts.csswg.org/cssom/#dom-cssstyledeclaration-csstext><code>cssText</code></a></dfn> attribute of <code id=dependencies:cssstyledeclaration><a data-x-internal=cssstyledeclaration href=https://drafts.csswg.org/cssom/#the-cssstyledeclaration-interface>CSSStyleDeclaration</a></code><li><dfn id=stylesheet><a href=https://drafts.csswg.org/cssom/#the-stylesheet-interface><code>StyleSheet</code></a></dfn> interface<li><dfn id=cssstylesheet><a href=https://drafts.csswg.org/cssom/#the-cssstylesheet-interface><code>CSSStyleSheet</code></a></dfn> interface<li><dfn id=create-a-css-style-sheet><a href=https://drafts.csswg.org/cssom/#create-a-css-style-sheet>create a CSS style sheet</a></dfn><li><dfn id=remove-a-css-style-sheet><a href=https://drafts.csswg.org/cssom/#remove-a-css-style-sheet>remove a CSS style sheet</a></dfn><li><dfn id=associated-css-style-sheet><a href=https://drafts.csswg.org/cssom/#associated-css-style-sheet>associated CSS style sheet</a></dfn><li><dfn id=create-a-constructed-cssstylesheet><a href=https://drafts.csswg.org/cssom/#create-a-constructed-cssstylesheet>create a constructed <code>CSSStyleSheet</code></a></dfn><li><dfn id=synchronously-replace-the-rules-of-a-cssstylesheet><a href=https://drafts.csswg.org/cssom/#synchronously-replace-the-rules-of-a-cssstylesheet>synchronously replace the rules of a <code>CSSStyleSheet</code></a></dfn><li><dfn id=disable-a-css-style-sheet><a href=https://drafts.csswg.org/cssom/#disable-a-css-style-sheet>disable a CSS style sheet</a></dfn><li>
      <dfn id=css-style-sheet><a href=https://drafts.csswg.org/cssom/#css-style-sheet>CSS style sheets</a></dfn> and their
      properties:
      <ul class=brief><li><dfn id=concept-css-style-sheet-type><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-type>type</a></dfn><li><dfn id=concept-css-style-sheet-location><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-location>location</a></dfn><li><dfn id=concept-css-style-sheet-parent-css-style-sheet><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-parent-css-style-sheet>parent CSS style sheet</a></dfn><li><dfn id=concept-css-style-sheet-owner-node><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-owner-node>owner node</a></dfn><li><dfn id=concept-css-style-sheet-owner-css-rule><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-owner-css-rule>owner CSS rule</a></dfn><li><dfn id=concept-css-style-sheet-media><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-media>media</a></dfn><li><dfn id=concept-css-style-sheet-title><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-title>title</a></dfn><li><dfn id=concept-css-style-sheet-alternate-flag><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-alternate-flag>alternate flag</a></dfn><li><dfn id=concept-css-style-sheet-disabled-flag><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-disabled-flag>disabled flag</a></dfn><li><dfn id=concept-css-style-sheet-css-rules><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-css-rules>CSS rules</a></dfn><li><dfn id=concept-css-style-sheet-origin-clean-flag><a href=https://drafts.csswg.org/cssom/#concept-css-style-sheet-origin-clean-flag>origin-clean flag</a></dfn></ul>
     <li><dfn id=css-style-sheet-set><a href=https://drafts.csswg.org/cssom/#css-style-sheet-set>CSS style sheet set</a></dfn><li><dfn id=css-style-sheet-set-name><a href=https://drafts.csswg.org/cssom/#css-style-sheet-set-name>CSS style sheet set name</a></dfn><li><dfn id=preferred-css-style-sheet-set-name><a href=https://drafts.csswg.org/cssom/#preferred-css-style-sheet-set-name>preferred CSS style sheet set name</a></dfn><li><dfn id=change-the-preferred-css-style-sheet-set-name><a href=https://drafts.csswg.org/cssom/#change-the-preferred-css-style-sheet-set-name>change the preferred CSS style sheet set name</a></dfn><li><dfn id=serializing-a-css-value><a href=https://drafts.csswg.org/cssom/#serialize-a-css-value>Serializing a CSS value</a></dfn><li><dfn id=run-the-resize-steps><a href=https://drafts.csswg.org/cssom-view/#document-run-the-resize-steps>run the resize steps</a></dfn><li><dfn id=run-the-scroll-steps><a href=https://drafts.csswg.org/cssom-view/#document-run-the-scroll-steps>run the scroll steps</a></dfn><li><dfn id=evaluate-media-queries-and-report-changes><a href=https://drafts.csswg.org/cssom-view/#evaluate-media-queries-and-report-changes>evaluate media queries and report changes</a></dfn><li><dfn id=scroll-a-target-into-view><a href=https://drafts.csswg.org/cssom-view/#scroll-a-target-into-view>Scroll a target into view</a></dfn><li><dfn id=scroll-to-the-beginning-of-the-document><a href=https://drafts.csswg.org/cssom-view/#scroll-to-the-beginning-of-the-document>Scroll to the beginning of the document</a></dfn><li>The <dfn id=event-resize><a href=https://drafts.csswg.org/cssom-view/#eventdef-window-resize><code>resize</code></a></dfn> event<li>The <dfn id=event-scroll><a href=https://drafts.csswg.org/cssom-view/#eventdef-document-scroll><code>scroll</code></a></dfn> event<li>The <dfn id=event-scrollend><a href=https://drafts.csswg.org/cssom-view/#eventdef-document-scrollend><code>scrollend</code></a></dfn> event<li><dfn id=set-up-browsing-context-features><a href=https://drafts.csswg.org/cssom-view/#set-up-browsing-context-features>set up browsing context features</a></dfn><li>The <dfn id=mouseevent-clientx><a href=https://drafts.csswg.org/cssom-view/#dom-mouseevent-clientx>clientX</a></dfn> and <dfn id=mouseevent-clienty><a href=https://drafts.csswg.org/cssom-view/#dom-mouseevent-clienty>clientY</a></dfn> extension attributes of the <a id=dependencies:mouseevent-3 href=https://w3c.github.io/uievents/#mouseevent data-x-internal=mouseevent>MouseEvent</a> interface</ul>

    <p>The following features and terms are defined in <cite>CSS Syntax</cite>:
    <a href=references.html#refsCSSSYNTAX>[CSSSYNTAX]</a></p>

    <ul class=brief><li><dfn id=conformant-style-sheet><a href=https://drafts.csswg.org/css-syntax/#conform-classes>conformant style sheet</a></dfn><li><dfn id=parse-a-list-of-component-values><a href=https://drafts.csswg.org/css-syntax/#parse-a-list-of-component-values>parse a list of component values</a></dfn><li><dfn id=parse-a-comma-separated-list-of-component-values><a href=https://drafts.csswg.org/css-syntax/#parse-a-comma-separated-list-of-component-values>parse a comma-separated list of component values</a></dfn><li><dfn id=component-value><a href=https://drafts.csswg.org/css-syntax/#component-value>component value</a></dfn><li><dfn id=environment-encoding><a href=https://drafts.csswg.org/css-syntax/#environment-encoding>environment encoding</a></dfn><li><dfn id=whitespace-token><a href=https://drafts.csswg.org/css-syntax/#typedef-whitespace-token>&lt;whitespace-token></a></dfn></ul>

    <p>The following terms are defined in <cite>Selectors</cite>: <a href=references.html#refsSELECTORS>[SELECTORS]</a></p>

    <ul class=brief><li><dfn id=selector-list><a href=https://drafts.csswg.org/selectors/#typedef-selector-list><code>&lt;selector-list></code></a></dfn><li><dfn id=parse-a-selector><a href=https://drafts.csswg.org/selectors/#parse-a-selector>parse a selector</a></dfn><li><dfn id=selector><a href=https://drafts.csswg.org/selectors/#selector>selector</a></dfn><li><dfn id=type-selector><a href=https://drafts.csswg.org/selectors/#type-selector>type selector</a></dfn><li><dfn id=attribute-selector><a href=https://drafts.csswg.org/selectors/#attribute-selector>attribute selector</a></dfn><li><dfn id=pseudo-class><a href=https://drafts.csswg.org/selectors/#pseudo-class>pseudo-class</a></dfn><li><dfn id=:focus-visible><a href=https://drafts.csswg.org/selectors/#the-focus-visible-pseudo><code>:focus-visible</code></a></dfn>
     pseudo-class<li><dfn id=indicate-focus><a href=https://drafts.csswg.org/selectors/#indicate-focus>indicate focus</a></dfn><li><dfn id=pseudo-element><a href=https://drafts.csswg.org/selectors/#pseudo-element>pseudo-element</a></dfn><li><dfn id=match-a-selector-against-an-element><a href=https://drafts.csswg.org/selectors/#match-a-selector-against-an-element>match a selector against an element</a></dfn><li><dfn id=scoping-root><a href=https://drafts.csswg.org/selectors/#scoping-root>scoping root</a></dfn></ul>

    <p>The following features are defined in <cite>CSS Values and Units</cite>:
    <a href=references.html#refsCSSVALUES>[CSSVALUES]</a></p>

    <ul class=brief><li><dfn id=length-2><a href=https://drafts.csswg.org/css-values/#lengths>&lt;length></a></dfn><li>The <dfn id="'em'"><a href=https://drafts.csswg.org/css-values/#em>'em'</a></dfn> unit<li>The <dfn id="'ex'"><a href=https://drafts.csswg.org/css-values/#ex>'ex'</a></dfn> unit<li>The <dfn id="'vw'"><a href=https://drafts.csswg.org/css-values/#vw>'vw'</a></dfn> unit<li>The <dfn id="'in'"><a href=https://drafts.csswg.org/css-values/#in>'in'</a></dfn> unit<li>The <dfn id="'px'"><a href=https://drafts.csswg.org/css-values/#px>'px'</a></dfn> unit<li>The <dfn id="'pt'"><a href=https://drafts.csswg.org/css-values/#pt>'pt'</a></dfn> unit<li>The <dfn id="'attr()'"><a href=https://drafts.csswg.org/css-values/#funcdef-attr>'attr()'</a></dfn> function<li>The <dfn id=math-functions><a href=https://drafts.csswg.org/css-values/#math-function>math functions</a></dfn></ul>

    <p>The following features are defined in <cite>CSS View Transitions</cite>:
    <a href=references.html#refsCSSVIEWTRANSITIONS>[CSSVIEWTRANSITIONS]</a></p>

    <ul class=brief><li><dfn id=perform-pending-transition-operations><a href=https://drafts.csswg.org/css-view-transitions/#perform-pending-transition-operations>perform pending transition operations</a></dfn><li><dfn id=rendering-suppression-for-view-transitions><a href=https://drafts.csswg.org/css-view-transitions/#document-rendering-suppression-for-view-transitions>rendering suppression for view transitions</a></dfn><li><dfn id=activate-view-transition><a href=https://drafts.csswg.org/css-view-transitions/#activate-view-transition>activate view transition</a></dfn><li><dfn id=viewtransition><a href=https://drafts.csswg.org/css-view-transitions/#viewtransition><code>ViewTransition</code></a></dfn><li><dfn id=view-transition-page-visibility-change-steps><a href=https://drafts.csswg.org/css-view-transitions/#view-transition-page-visibility-change-steps>view transition page visibility change steps</a></dfn><li><dfn id=resolving-inbound-cross-document-view-transition><a href=https://drafts.csswg.org/css-view-transitions-2/#resolve-inbound-cross-document-view-transition>resolving inbound cross-document view-transition</a></dfn><li><dfn id=setting-up-a-cross-document-view-transition><a href=https://drafts.csswg.org/css-view-transitions-2/#setup-cross-document-view-transition>setting up a cross-document view-transition</a></dfn><li><dfn id=can-navigation-trigger-a-cross-document-view-transition><a href=https://drafts.csswg.org/css-view-transitions-2/#can-navigation-trigger-a-cross-document-view-transition>can navigation trigger a cross-document view-transition?</a></dfn>
    </ul>

    <p>The term <dfn id=css-styling-attribute><a href=https://drafts.csswg.org/css-style-attr/#style-attribute>style attribute</a></dfn> is
    defined in <cite>CSS Style Attributes</cite>. <a href=references.html#refsCSSATTR>[CSSATTR]</a></p>

    <p>The following terms are defined in the <cite>CSS Cascading and Inheritance</cite>:
    <a href=references.html#refsCSSCASCADE>[CSSCASCADE]</a></p>

    <ul class=brief><li><dfn id=cascaded-value><a href=https://drafts.csswg.org/css-cascade/#cascaded-value>cascaded value</a></dfn><li><dfn id=specified-value><a href=https://drafts.csswg.org/css-cascade/#specified-value>specified value</a></dfn><li><dfn id=computed-value><a href=https://drafts.csswg.org/css-cascade/#computed-value>computed value</a></dfn><li><dfn id=used-value><a href=https://drafts.csswg.org/css-cascade/#used-value>used value</a></dfn><li><dfn id=cascade-origin><a href=https://drafts.csswg.org/css-cascade/#origin>cascade origin</a></dfn><li><dfn id=author-origin><a href=https://drafts.csswg.org/css-cascade/#cascade-origin-author>Author Origin</a></dfn><li><dfn id=user-origin><a href=https://drafts.csswg.org/css-cascade/#cascade-origin-user>User Origin</a></dfn><li><dfn id=user-agent-origin><a href=https://drafts.csswg.org/css-cascade/#cascade-origin-ua>User Agent Origin</a></dfn><li><dfn id=animation-origin><a href=https://drafts.csswg.org/css-cascade/#cascade-origin-animation>Animation Origin</a></dfn><li><dfn id=transition-origin><a href=https://drafts.csswg.org/css-cascade/#cascade-origin-transition>Transition Origin</a></dfn><li><dfn id=initial-value><a href=https://drafts.csswg.org/css-cascade/#initial-value>initial value</a></dfn></ul>

    <p>The <code id=dependencies:canvasrenderingcontext2d><a href=canvas.html#canvasrenderingcontext2d>CanvasRenderingContext2D</a></code> object's use of fonts depends on the features
    described in the CSS <cite>Fonts</cite> and <cite>Font Loading</cite> specifications, including
    in particular <dfn id=fontface><code>FontFace</code></dfn> objects and the <dfn id=font-source><a href=https://drafts.csswg.org/css-font-loading/#font-source>font source</a></dfn> concept.
    <a href=references.html#refsCSSFONTS>[CSSFONTS]</a> <a href=references.html#refsCSSFONTLOAD>[CSSFONTLOAD]</a></p>

    <p>The following interfaces and terms are defined in <cite>Geometry Interfaces</cite>:
    <a href=references.html#refsGEOMETRY>[GEOMETRY]</a></p>

    <ul class=brief><li><dfn id=dommatrix><a href=https://drafts.fxtf.org/geometry/#dommatrix><code>DOMMatrix</code></a></dfn> interface, and associated
         <dfn id=m11-element><a href=https://drafts.fxtf.org/geometry/#matrix-m11-element>m11 element</a></dfn>,
         <dfn id=m12-element><a href=https://drafts.fxtf.org/geometry/#matrix-m12-element>m12 element</a></dfn>,
         <dfn id=m21-element><a href=https://drafts.fxtf.org/geometry/#matrix-m21-element>m21 element</a></dfn>,
         <dfn id=m22-element><a href=https://drafts.fxtf.org/geometry/#matrix-m22-element>m22 element</a></dfn>,
         <dfn id=m41-element><a href=https://drafts.fxtf.org/geometry/#matrix-m41-element>m41 element</a></dfn>, and
         <dfn id=m42-element><a href=https://drafts.fxtf.org/geometry/#matrix-m42-element>m42 element</a></dfn><li><dfn id=dommatrix2dinit><a href=https://drafts.fxtf.org/geometry/#dictdef-dommatrix2dinit><code>DOMMatrix2DInit</code></a></dfn> and
         <dfn id=dommatrixinit><a href=https://drafts.fxtf.org/geometry/#dictdef-dommatrixinit><code>DOMMatrixInit</code></a></dfn> dictionaries<li>The <dfn id=create-a-dommatrix-from-a-dictionary><a href=https://drafts.fxtf.org/geometry/#create-a-dommatrix-from-the-dictionary>create a <code>DOMMatrix</code> from a dictionary</a></dfn>
         and <dfn id=create-a-dommatrix-from-a-2d-dictionary><a href=https://drafts.fxtf.org/geometry/#create-a-dommatrix-from-the-2d-dictionary>create a <code>DOMMatrix</code> from a 2D dictionary</a></dfn>
         algorithms for <code id=dependencies:dommatrix2dinit><a data-x-internal=dommatrix2dinit href=https://drafts.fxtf.org/geometry/#dictdef-dommatrix2dinit>DOMMatrix2DInit</a></code> or <code id=dependencies:dommatrixinit><a data-x-internal=dommatrixinit href=https://drafts.fxtf.org/geometry/#dictdef-dommatrixinit>DOMMatrixInit</a></code><li>The <dfn id=dompointinit><a href=https://drafts.fxtf.org/geometry/#dictdef-dompointinit><code>DOMPointInit</code></a></dfn> dictionary, and associated
         <dfn id=dompointinit-x><a href=https://drafts.fxtf.org/geometry/#dom-dompointinit-x>x</a></dfn> and
         <dfn id=dompointinit-y><a href=https://drafts.fxtf.org/geometry/#dom-dompointinit-y>y</a></dfn> members<li><dfn id=matrix-multiplication><a href=https://drafts.fxtf.org/geometry/#matrix-multiply>Matrix multiplication</a></dfn></ul>

    <p>The following terms are defined in the <cite>CSS Scoping</cite>: <a href=references.html#refsCSSSCOPING>[CSSSCOPING]</a></p>

    <ul class=brief><li><dfn id=flat-tree><a href=https://drafts.csswg.org/css-scoping/#flat-tree>flat tree</a></dfn></ul>

    <p>The following terms and features are defined in <cite>CSS Color Adjustment</cite>:
    <a href=references.html#refsCSSCOLORADJUST>[CSSCOLORADJUST]</a></p>

    <ul class=brief><li><dfn id="'color-scheme'"><a href=https://drafts.csswg.org/css-color-adjust/#color-scheme-prop>'color-scheme'</a></dfn><li><dfn id="page's-supported-color-schemes"><a href=https://drafts.csswg.org/css-color-adjust/#pages-supported-color-schemes>page's supported color-schemes</a></dfn></ul>

    <p>The following terms are defined in <cite>CSS Pseudo-Elements</cite>: <a href=references.html#refsCSSPSEUDO>[CSSPSEUDO]</a></p>

    <ul class=brief><li><dfn id="'::details-content'"><a href=https://drafts.csswg.org/css-pseudo/#details-content-pseudo>'::details-content'</a></dfn><li><dfn id="'::file-selector-button'"><a href=https://drafts.csswg.org/css-pseudo/#file-selector-button-pseudo>'::file-selector-button'</a></dfn></ul>

    <p>The following terms are defined in <cite>CSS Containment</cite>: <a href=references.html#refsCSSCONTAIN>[CSSCONTAIN]</a></p>

    <ul class=brief><li><dfn id=skips-its-contents><a href=https://drafts.csswg.org/css-contain/#skips-its-contents>skips its contents</a></dfn><li><dfn id=relevant-to-the-user><a href=https://drafts.csswg.org/css-contain/#relevant-to-the-user>relevant to the user</a></dfn><li><dfn id=proximity-to-the-viewport><a href=https://drafts.csswg.org/css-contain/#proximity-to-the-viewport>proximity to the viewport</a></dfn><li><dfn id=layout-containment><a href=https://drafts.csswg.org/css-contain/#containment-layout>layout containment</a></dfn><li><dfn id="'content-visibility'"><a href=https://drafts.csswg.org/css-contain/#content-visibility>'content-visibility'</a></dfn> property<li><dfn id=content-visibility-auto><a href=https://drafts.csswg.org/css-contain/#propdef-content-visibility>'auto'</a></dfn> value for <a id="dependencies:'content-visibility'" href=https://drafts.csswg.org/css-contain/#content-visibility data-x-internal="'content-visibility'">'content-visibility'</a></ul>

    <p>The following terms are defined in <cite>CSS Anchor Positioning</cite>: <a href=references.html#refsCSSANCHOR>[CSSANCHOR]</a></p>

    <ul class=brief><li><dfn id=implicit-anchor-element><a href=https://drafts.csswg.org/css-anchor-position/#implicit-anchor-element>implicit anchor element</a></dfn></ul>
   <dt>Intersection Observer<dd>
    <p>The following term is defined in <cite>Intersection Observer</cite>:
    <a href=references.html#refsINTERSECTIONOBSERVER>[INTERSECTIONOBSERVER]</a></p>

    <ul class=brief><li><dfn id=run-the-update-intersection-observations-steps><a href=https://w3c.github.io/IntersectionObserver/#run-the-update-intersection-observations-steps>run the update intersection observations steps</a></dfn><li><dfn id=intersectionobserver><a href=https://w3c.github.io/IntersectionObserver/#intersectionobserver><code>IntersectionObserver</code></a></dfn><li><dfn id=intersectionobserverinit><a href=https://w3c.github.io/IntersectionObserver/#dictdef-intersectionobserverinit><code>IntersectionObserverInit</code></a></dfn><li><dfn id=dom-intersectionobserver-observe><a href=https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-observe><code>observe</code></a></dfn><li><dfn id=dom-intersectionobserver-unobserve><a href=https://w3c.github.io/IntersectionObserver/#dom-intersectionobserver-unobserve><code>unobserve</code></a></dfn><li><dfn id=dom-intersectionobserverentry-isintersecting><a href=https://w3c.github.io/IntersectionObserver/#dom-intersectionobserverentry-isintersecting><code>isIntersecting</code></a></dfn><li><dfn id=dom-intersectionobserverentry-target><a href=https://w3c.github.io/IntersectionObserver/#dom-intersectionobserverentry-target><code>target</code></a></dfn></ul>
   <dt>Resize Observer<dd>
    <p>The following terms are defined in <cite>Resize Observer</cite>:
    <a href=references.html#refsRESIZEOBSERVER>[RESIZEOBSERVER]</a></p>

    <ul class=brief><li><dfn id=gather-active-resize-observations-at-depth><a href=https://drafts.csswg.org/resize-observer-1/#gather-active-observations-h>gather active resize observations at depth</a></dfn><li><dfn id=has-active-resize-observations><a href=https://drafts.csswg.org/resize-observer-1/#has-active-observations-h>has active resize observations</a></dfn><li><dfn id=has-skipped-resize-observations><a href=https://drafts.csswg.org/resize-observer-1/#has-skipped-observations-h>has skipped resize observations</a></dfn><li><dfn id=broadcast-active-resize-observations><a href=https://drafts.csswg.org/resize-observer-1/#broadcast-resize-notifications-h>broadcast active resize observations</a></dfn><li><dfn id=deliver-resize-loop-error><a href=https://drafts.csswg.org/resize-observer-1/#deliver-resize-error>deliver resize loop error</a></dfn></ul>
   <dt>WebGL<dd>
    <p>The following interfaces are defined in the WebGL specifications: <a href=references.html#refsWEBGL>[WEBGL]</a></p>

    <ul class=brief><li><dfn id=webglrenderingcontext><a href=https://www.khronos.org/registry/webgl/specs/latest/1.0/#WebGLRenderingContext><code>WebGLRenderingContext</code></a></dfn> interface<li><dfn id=webgl2renderingcontext><a href=https://www.khronos.org/registry/webgl/specs/latest/2.0/#WebGL2RenderingContext><code>WebGL2RenderingContext</code></a></dfn> interface<li><dfn id=webglcontextattributes><a href=https://www.khronos.org/registry/webgl/specs/latest/1.0/#WebGLContextAttributes><code>WebGLContextAttributes</code></a></dfn> dictionary</ul>
   <dt>WebGPU<dd>
    <p>The following interfaces are defined in <cite>WebGPU</cite>: <a href=references.html#refsWEBGPU>[WEBGPU]</a></p>

    <ul class=brief><li><dfn id=gpucanvascontext><a href=https://gpuweb.github.io/gpuweb/#canvas-context><code>GPUCanvasContext</code></a></dfn> interface</ul>
   <dt>WebVTT<dd>
    <p>Implementations may support WebVTT as a text track format for subtitles, captions, metadata,
    etc., for media resources. <a href=references.html#refsWEBVTT>[WEBVTT]</a></p>

    <p>The following terms, used in this specification, are defined in <cite>WebVTT</cite>:</p>

    <ul class=brief><li><dfn id=webvtt-file><a href=https://w3c.github.io/webvtt/#webvtt-file>WebVTT file</a></dfn><li><dfn id=webvtt-file-using-cue-text><a href=https://w3c.github.io/webvtt/#webvtt-file-using-cue-text>WebVTT file using cue text</a></dfn><li><dfn id=webvtt-file-using-only-nested-cues><a href=https://w3c.github.io/webvtt/#webvtt-file-using-only-nested-cues>WebVTT file using only nested cues</a></dfn><li><dfn id=webvtt-parser><a href=https://w3c.github.io/webvtt/#webvtt-parser>WebVTT parser</a></dfn><li>The <dfn id=rules-for-updating-the-display-of-webvtt-text-tracks><a href=https://w3c.github.io/webvtt/#rules-for-updating-the-display-of-webvtt-text-tracks>rules for updating the display of WebVTT text tracks</a></dfn><li>The WebVTT <dfn id=text-track-cue-writing-direction><a href=https://w3c.github.io/webvtt/#webvtt-cue-writing-direction>text track cue writing direction</a></dfn><li><dfn id=vttcue><a href=https://w3c.github.io/webvtt/#vttcue><code>VTTCue</code></a></dfn> interface</ul>
   <dt>ARIA<dd>
    <p>The <dfn id=attr-aria-role data-dfn-type=element-attr><code>role</code></dfn> attribute is defined in
    <cite>Accessible Rich Internet Applications</cite> (<cite>ARIA</cite>), as are the following
    roles: <a href=references.html#refsARIA>[ARIA]</a></p>

    <ul class=brief><li><dfn id=attr-aria-role-button><a href=https://w3c.github.io/aria/#button><code>button</code></a></dfn><li><dfn id=attr-aria-role-presentation><a href=https://w3c.github.io/aria/#presentation><code>presentation</code></a></dfn></ul>

    <p>In addition, the following <dfn id=attr-aria-*><code>aria-*</code></dfn> content
    attributes are defined in <cite>ARIA</cite>: <a href=references.html#refsARIA>[ARIA]</a></p>

    <ul class=brief><li><dfn id=attr-aria-checked><a href=https://w3c.github.io/aria/#aria-checked><code>aria-checked</code></a></dfn><li><dfn id=attr-aria-describedby><a href=https://w3c.github.io/aria/#aria-describedby><code>aria-describedby</code></a></dfn><li><dfn id=attr-aria-disabled><a href=https://w3c.github.io/aria/#aria-disabled><code>aria-disabled</code></a></dfn><li><dfn id=attr-aria-label><a href=https://w3c.github.io/aria/#aria-label><code>aria-label</code></a></dfn></ul>

    <p>Finally, the following terms are defined in <cite>ARIA</cite>: <a href=references.html#refsARIA>[ARIA]</a></p>

    <ul class=brief><li><dfn id=role><a href=https://w3c.github.io/aria/#dfn-role>role</a></dfn><li><dfn id=concept-accessible-name><a href=https://w3c.github.io/aria/#dfn-accessible-name>accessible name</a></dfn><li>The <dfn id=ariamixin><a href=https://w3c.github.io/aria/#ARIAMixin><code>ARIAMixin</code></a></dfn> interface, with its associated
             <dfn id=ariamixin-getter-steps><a href=https://w3c.github.io/aria/#dfn-ariamixin-getter-steps><code>ARIAMixin</code> getter steps</a></dfn> and
             <dfn id=ariamixin-setter-steps><a href=https://w3c.github.io/aria/#dfn-ariamixin-setter-steps><code>ARIAMixin</code> setter steps</a></dfn> hooks, and its
             <dfn id=dom-ariamixin-role><a href=https://w3c.github.io/aria/#idl-def-ariamixin-role><code>role</code></a></dfn> and
             <dfn id=dom-ariamixin-aria*><a href=https://w3c.github.io/aria/#idl-def-ariamixin-ariaactivedescendantelement><code>aria*</code></a></dfn> attributes</ul>
   <dt>Content Security Policy<dd>
    <p>The following terms are defined in <cite>Content Security Policy</cite>: <a href=references.html#refsCSP>[CSP]</a></p>

    <ul class=brief><li><dfn id=content-security-policy><a href=https://w3c.github.io/webappsec-csp/#content-security-policy-object>Content Security Policy</a></dfn><li><dfn id=csp-disposition><a href=https://w3c.github.io/webappsec-csp/#policy-disposition>disposition</a></dfn><li><dfn id=csp-directive-set><a href=https://w3c.github.io/webappsec-csp/#policy-directive-set>directive set</a></dfn><li><dfn id=content-security-policy-directive><a href=https://w3c.github.io/webappsec-csp/#directives>Content Security Policy directive</a></dfn><li><dfn id=concept-csp-list><a href=https://w3c.github.io/webappsec-csp/#csp-list>CSP list</a></dfn><li>The <dfn id=content-security-policy-syntax><a href=https://w3c.github.io/webappsec-csp/#grammardef-serialized-policy>Content Security Policy syntax</a></dfn><li><dfn id=enforce-the-policy><a href=https://w3c.github.io/webappsec-csp/#enforced>enforce the policy</a></dfn><li>The <dfn id=parse-a-serialized-content-security-policy><a href=https://w3c.github.io/webappsec-csp/#parse-serialized-policy>parse a serialized Content Security Policy</a></dfn> algorithm<li>The <dfn id=run-csp-initialization-for-a-document><a href=https://w3c.github.io/webappsec-csp/#run-document-csp-initialization>Run CSP initialization for a Document</a></dfn> algorithm<li>The <dfn id=run-csp-initialization-for-a-global-object><a href=https://w3c.github.io/webappsec-csp/#run-global-object-csp-initialization>Run CSP initialization for a global object</a></dfn> algorithm<li>The <dfn id="should-element's-inline-behavior-be-blocked-by-content-security-policy"><a href=https://w3c.github.io/webappsec-csp/#should-block-inline>Should element's inline behavior be blocked by Content Security Policy?</a></dfn> algorithm<li>The <dfn id=should-navigation-request-of-type-be-blocked-by-content-security-policy><a href=https://w3c.github.io/webappsec-csp/#should-block-navigation-request>Should navigation request of type be blocked by Content Security Policy?</a></dfn> algorithm<li>The <dfn id=should-navigation-response-to-navigation-request-of-type-in-target-be-blocked-by-content-security-policy><a href=https://w3c.github.io/webappsec-csp/#should-block-navigation-response>Should navigation response to navigation request of type in target be blocked by Content Security Policy?</a></dfn> algorithm<li>The <dfn id=report-uri-directive><a href=https://w3c.github.io/webappsec-csp/#report-uri><code>report-uri</code> directive</a></dfn><li>The <dfn id=csp-ensurecspdoesnotblockstringcompilation><a href=https://w3c.github.io/webappsec-csp/#can-compile-strings>EnsureCSPDoesNotBlockStringCompilation</a></dfn> abstract operation<li>The <dfn id=is-base-allowed-for-document><a href=https://w3c.github.io/webappsec-csp/#allow-base-for-document>Is base allowed for Document?</a></dfn> algorithm<li>The <dfn id=frame-ancestors-directive><a href=https://w3c.github.io/webappsec-csp/#frame-ancestors><code>frame-ancestors</code> directive</a></dfn><li>The <dfn id=sandbox-directive><a href=https://w3c.github.io/webappsec-csp/#sandbox><code>sandbox</code> directive</a></dfn><li>The <dfn id=contains-a-header-delivered-content-security-policy><a href=https://w3c.github.io/webappsec-csp/#contains-a-header-delivered-content-security-policy>contains a header-delivered Content Security Policy</a></dfn> property.<li>The <dfn id=parse-response-csp><a href=https://w3c.github.io/webappsec-csp/#parse-response-csp>Parse a response's Content Security Policies</a></dfn> algorithm.<li><dfn id=securitypolicyviolationevent><a href=https://w3c.github.io/webappsec-csp/#securitypolicyviolationevent><code>SecurityPolicyViolationEvent</code></a></dfn> interface<li>The <dfn id=event-securitypolicyviolation><a href=https://w3c.github.io/webappsec-csp/#eventdef-globaleventhandlers-securitypolicyviolation><code>securitypolicyviolation</code></a></dfn> event</ul>
   <dt>Service Workers<dd>
    <p>The following terms are defined in <cite>Service Workers</cite>: <a href=references.html#refsSW>[SW]</a></p>

    <ul class=brief><li><dfn id=dfn-active-worker><a href=https://w3c.github.io/ServiceWorker/#dfn-active-worker>active worker</a></dfn><li><dfn id=dfn-client-message-queue><a href=https://w3c.github.io/ServiceWorker/#dfn-client-message-queue>client message queue</a></dfn><li><dfn id=dfn-control><a href=https://w3c.github.io/ServiceWorker/#dfn-control>control</a></dfn><li><dfn id=on-fetch-request-algorithm><a href=https://w3c.github.io/ServiceWorker/#on-fetch-request-algorithm>handle fetch</a></dfn><li><dfn id=scope-match-algorithm><a href=https://w3c.github.io/ServiceWorker/#scope-match-algorithm>match service worker registration</a></dfn><li><dfn id=dfn-service-worker><a href=https://w3c.github.io/ServiceWorker/#dfn-service-worker>service worker</a></dfn><li><dfn id=serviceworkercontainer-service-worker-client><a href=https://w3c.github.io/ServiceWorker/#serviceworkercontainer-service-worker-client>service worker client</a></dfn><li><dfn id=service-worker-registration><a href=https://w3c.github.io/service-workers/#dfn-service-worker-registration>service worker registration</a></dfn><li><dfn id=serviceworker><a href=https://w3c.github.io/ServiceWorker/#serviceworker><code>ServiceWorker</code></a></dfn> interface<li><dfn id=serviceworkercontainer><a href=https://w3c.github.io/ServiceWorker/#serviceworkercontainer><code>ServiceWorkerContainer</code></a></dfn> interface<li><dfn id=serviceworkerglobalscope><a href=https://w3c.github.io/ServiceWorker/#serviceworkerglobalscope><code>ServiceWorkerGlobalScope</code></a></dfn> interface<li><dfn id=service-worker-unregister><a href=https://w3c.github.io/service-workers/#navigator-service-worker-unregister><code>unregister</code></a></dfn></ul>
   <dt>Secure Contexts<dd>
    <p>The following algorithms are defined in <cite>Secure Contexts</cite>:
    <a href=references.html#refsSECURE-CONTEXTS>[SECURE-CONTEXTS]</a></p>

    <ul class=brief><li><dfn id=is-url-potentially-trustworthy><a href=https://w3c.github.io/webappsec-secure-contexts/#potentially-trustworthy-url>Is url potentially trustworthy?</a></dfn></ul>
   <dt>Permissions Policy<dd>
    <p>The following terms are defined in <cite>Permissions Policy</cite>:
    <a href=references.html#refsPERMISSIONSPOLICY>[PERMISSIONSPOLICY]</a></p>

    <ul class=brief><li><dfn id=concept-permissions-policy><a href=https://w3c.github.io/webappsec-feature-policy/#permissions-policy>permissions policy</a></dfn><li><dfn id=concept-policy-controlled-feature><a href=https://w3c.github.io/webappsec-feature-policy/#policy-controlled-feature>policy-controlled feature</a></dfn><li><dfn id=concept-container-policy><a href=https://w3c.github.io/webappsec-feature-policy/#container-policy>container policy</a></dfn><li><dfn id=concept-serialized-permissions-policy><a href=https://w3c.github.io/webappsec-feature-policy/#serialized-permissions-policy>serialized permissions policy</a></dfn><li><dfn id=concept-default-allowlist><a href=https://w3c.github.io/webappsec-feature-policy/#default-allowlist>default allowlist</a></dfn><li>The <dfn id=creating-a-permissions-policy><a href=https://w3c.github.io/webappsec-feature-policy/#create-for-navigable>creating a permissions policy</a></dfn> algorithm<li>The <dfn id=creating-a-permissions-policy-from-a-response><a href=https://w3c.github.io/webappsec-feature-policy/#create-from-response>creating a permissions policy from a response</a></dfn> algorithm<li>The <dfn id=is-feature-enabled><a href=https://w3c.github.io/webappsec-feature-policy/#is-feature-enabled>is feature enabled by policy for origin</a></dfn> algorithm<li>The <dfn id=process-permissions-policy-attributes><a href=https://w3c.github.io/webappsec-feature-policy/#process-permissions-policy-attributes>process permissions policy attributes</a></dfn> algorithm</ul>
   <dt>Payment Request API<dd>
    <p>The following feature is defined in <cite>Payment Request API</cite>:
    <a href=references.html#refsPAYMENTREQUEST>[PAYMENTREQUEST]</a></p>

    <ul class=brief><li><dfn id=paymentrequest><a href=https://w3c.github.io/payment-request/#dom-paymentrequest><code>PaymentRequest</code></a></dfn> interface</ul>
   <dt>MathML<dd>
    <p>While support for MathML as a whole is not required by this specification (though it is
    encouraged, at least for web browsers), certain features depend upon small parts of MathML being
    implemented. <a href=references.html#refsMATHML>[MATHML]</a></p>

    <p>The following features are defined in <cite>Mathematical Markup Language</cite>
    (<cite>MathML</cite>):</p>

    <ul class=brief><li><dfn id=mathml-annotation-xml><a href=https://w3c.github.io/mathml-core/#dfn-annotation-xml>MathML <code>annotation-xml</code></a></dfn> element<li><dfn id=mathml-math><a href=https://w3c.github.io/mathml-core/#the-top-level-math-element>MathML <code>math</code></a></dfn> element<li><dfn id=mathml-merror><a href=https://w3c.github.io/mathml-core/#error-message-merror>MathML <code>merror</code></a></dfn> element<li><dfn id=mathml-mi><a href=https://w3c.github.io/mathml-core/#the-mi-element>MathML <code>mi</code></a></dfn> element<li><dfn id=mathml-mn><a href=https://w3c.github.io/mathml-core/#number-mn>MathML <code>mn</code></a></dfn> element<li><dfn id=mathml-mo><a href=https://w3c.github.io/mathml-core/#operator-fence-separator-or-accent-mo>MathML <code>mo</code></a></dfn> element<li><dfn id=mathml-ms><a href=https://w3c.github.io/mathml-core/#string-literal-ms>MathML <code>ms</code></a></dfn> element<li><dfn id=mathml-mtext><a href=https://w3c.github.io/mathml-core/#text-mtext>MathML <code>mtext</code></a></dfn> element</ul>
   <dt>SVG<dd>
    <p>While support for SVG as a whole is not required by this specification (though it is
    encouraged, at least for web browsers), certain features depend upon parts of SVG being
    implemented.</p>

    <p>User agents that implement SVG must implement the <cite>SVG 2</cite> specification, and not
    any earlier revisions.</p>

    <p>The following features are defined in the <cite>SVG 2</cite> specification:
    <a href=references.html#refsSVG>[SVG]</a></p>

    <ul class=brief><li><dfn id=svgelement><a href=https://svgwg.org/svg2-draft/types.html#InterfaceSVGElement><code>SVGElement</code></a></dfn> interface<li><dfn id=svgimageelement><a href=https://svgwg.org/svg2-draft/embedded.html#InterfaceSVGImageElement><code>SVGImageElement</code></a></dfn> interface<li><dfn id=svgscriptelement><a href=https://svgwg.org/svg2-draft/interact.html#InterfaceSVGScriptElement><code>SVGScriptElement</code></a></dfn> interface<li><dfn id=svgsvgelement><a href=https://svgwg.org/svg2-draft/struct.html#InterfaceSVGSVGElement><code>SVGSVGElement</code></a></dfn> interface<li><dfn id=svg-a><a href=https://svgwg.org/svg2-draft/linking.html#AElement>SVG <code>a</code></a></dfn> element<li><dfn id=svg-desc><a href=https://svgwg.org/svg2-draft/struct.html#DescElement>SVG <code>desc</code></a></dfn> element<li><dfn id=svg-foreignobject><a href=https://svgwg.org/svg2-draft/embedded.html#ForeignObjectElement>SVG <code>foreignObject</code></a></dfn> element<li><dfn id=svg-image><a href=https://svgwg.org/svg2-draft/embedded.html#ImageElement>SVG <code>image</code></a></dfn> element<li><dfn id=svg-script><a href=https://svgwg.org/svg2-draft/interact.html#ScriptElement>SVG <code>script</code></a></dfn> element<li><dfn id=svg-svg><a href=https://svgwg.org/svg2-draft/struct.html#SVGElement>SVG <code>svg</code></a></dfn> element<li><dfn id=svg-title><a href=https://svgwg.org/svg2-draft/struct.html#TitleElement>SVG <code>title</code></a></dfn> element<li><dfn id=svg-use><a href=https://svgwg.org/svg2-draft/struct.html#UseElement>SVG <code>use</code></a></dfn> element<li><dfn id=svg-text-rendering><a href=https://svgwg.org/svg2-draft/painting.html#TextRendering>SVG <code>text-rendering</code></a></dfn> property</ul>
   <dt>Filter Effects<dd>
    <p>The following features are defined in <cite>Filter Effects</cite>: <a href=references.html#refsFILTERS>[FILTERS]</a></p>

    <ul class=brief><li><dfn id=filter-value-list><a href=https://drafts.fxtf.org/filter-effects/#typedef-filter-value-list>&lt;filter-value-list></a></dfn></ul>
   <dt>Compositing<dd>
    <p>The following features are defined in <cite>Compositing and Blending</cite>:
    <a href=references.html#refsCOMPOSITE>[COMPOSITE]</a></p>

    <ul class=brief><li><dfn id=blend-mode><a href=https://drafts.fxtf.org/compositing/#ltblendmodegt>&lt;blend-mode></a></dfn><li><dfn id=composite-mode><a href=https://drafts.fxtf.org/compositing/#compositemode>&lt;composite-mode></a></dfn><li><dfn id=gcop-source-over><a href=https://drafts.fxtf.org/compositing/#porterduffcompositingoperators_srcover>source-over</a></dfn><li><dfn id=gcop-copy><a href=https://drafts.fxtf.org/compositing/#porterduffcompositingoperators_src>copy</a></dfn></ul>
   <dt>Cooperative Scheduling of Background Tasks<dd>
    <p>The following features are defined in <cite>Cooperative Scheduling of Background
    Tasks</cite>: <a href=references.html#refsREQUESTIDLECALLBACK>[REQUESTIDLECALLBACK]</a></p>

    <ul class=brief><li><dfn id=requestidlecallback()><a href=https://w3c.github.io/requestidlecallback/#the-requestidlecallback-method><code>requestIdleCallback()</code></a></dfn><li><dfn id=start-an-idle-period-algorithm><a href=https://w3c.github.io/requestidlecallback/#start-an-idle-period-algorithm>start an idle period algorithm</a></dfn></ul>
   <dt>Screen Orientation<dd>
    <p>The following terms are defined in <cite>Screen Orientation</cite>:
    <a href=references.html#refsSCREENORIENTATION>[SCREENORIENTATION]</a></p>

    <ul><li><dfn id=screen-orientation-change-steps><a href=https://w3c.github.io/screen-orientation/#dfn-screen-orientation-change-steps>screen orientation change steps</a></dfn></ul>
   <dt>Storage<dd>
    <p>The following terms are defined in <cite>Storage</cite>: <a href=references.html#refsSTORAGE>[STORAGE]</a></p>

    <ul class=brief><li><dfn id=storage-key><a href=https://storage.spec.whatwg.org/#storage-key>storage key</a></dfn><li><dfn id=obtain-a-local-storage-bottle-map><a href=https://storage.spec.whatwg.org/#obtain-a-local-storage-bottle-map>obtain a local storage bottle map</a></dfn><li><dfn id=obtain-a-session-storage-bottle-map><a href=https://storage.spec.whatwg.org/#obtain-a-session-storage-bottle-map>obtain a session storage bottle map</a></dfn><li><dfn id=obtain-a-storage-key-for-non-storage-purposes><a href=https://storage.spec.whatwg.org/#obtain-a-storage-key-for-non-storage-purposes>obtain a storage key for non-storage purposes</a></dfn><li><dfn id=storage-key-equal><a href=https://storage.spec.whatwg.org/#storage-key-equal>storage key equal</a></dfn><li><dfn id=storage-proxy-map><a href=https://storage.spec.whatwg.org/#storage-proxy-map>storage proxy map</a></dfn><li><dfn id=legacy-clone-a-traversable-storage-shed><a href=https://storage.spec.whatwg.org/#legacy-clone-a-traversable-storage-shed>legacy-clone a traversable storage shed</a></dfn></ul>
   <dt>Web App Manifest<dd>
    <p>The following features are defined in <cite>Web App Manifest</cite>: <a href=references.html#refsMANIFEST>[MANIFEST]</a></p>

    <ul class=brief><li><dfn id=application-manifest><a href=https://w3c.github.io/manifest/#dfn-manifest>application manifest</a></dfn><li><dfn id=installed-web-application><a href=https://w3c.github.io/manifest/#dfn-installed-web-application>installed web application</a></dfn><li><dfn id=process-the-manifest><a href=https://w3c.github.io/manifest/#dfn-processing-a-manifest>process the manifest</a></dfn></ul>
   <dt>WebAssembly JavaScript Interface: ESM Integration<dd>
    <p>The following terms are defined in <cite>WebAssembly JavaScript Interface: ESM Integration</cite>: <a href=references.html#refsWASMESM>[WASMESM]</a></p>

    <ul class=brief><li><dfn id=webassembly-module-record><a href=https://webassembly.github.io/esm-integration/js-api/index.html#webassembly-module-record>WebAssembly Module Record</a></dfn><li><dfn id=parse-a-webassembly-module><a href=https://webassembly.github.io/esm-integration/js-api/index.html#parse-a-webassembly-module>parse a WebAssembly module</a></dfn></ul>
   <dt>WebCodecs<dd>
    <p>The following features are defined in <cite>WebCodecs</cite>: <a href=references.html#refsWEBCODECS>[WEBCODECS]</a></p>

    <ul class=brief><li><dfn id=videoframe><a href=https://w3c.github.io/webcodecs/#videoframe-interface><code>VideoFrame</code></a></dfn> interface.<li><dfn id=display-width><a href=https://w3c.github.io/webcodecs/#dom-videoframe-display-width-slot>[[display width]]</a></dfn><li><dfn id=display-height><a href=https://w3c.github.io/webcodecs/#dom-videoframe-display-height-slot>[[display height]]</a></dfn></ul>
   <dt>WebDriver<dd>
    <p>The following terms are defined in <cite>WebDriver</cite>: <a href=references.html#refsWEBDRIVER>[WEBDRIVER]</a></p>

    <ul class=brief><li><dfn id=extension-command><a href=https://w3c.github.io/webdriver/#dfn-extension-commands>extension command</a></dfn><li><dfn id=remote-end-steps><a href=https://w3c.github.io/webdriver/#dfn-remote-end-steps>remote end steps</a></dfn><li><dfn id=webdriver-error><a href=https://w3c.github.io/webdriver/#dfn-errors>WebDriver error</a></dfn><li><dfn id=webdriver-error-code><a href=https://w3c.github.io/webdriver/#dfn-error-code>WebDriver error code</a></dfn><li><dfn id=invalid-argument><a href=https://w3c.github.io/webdriver/#dfn-invalid-argument>invalid argument</a></dfn><li><dfn id=getting-a-property><a href=https://w3c.github.io/webdriver/#dfn-getting-properties>getting a property</a></dfn><li><dfn id=success-value><a href=https://w3c.github.io/webdriver/#dfn-success>success</a></dfn><li><dfn id="webdriver's-security-considerations"><a href=https://w3c.github.io/webdriver/#security>WebDriver's security considerations</a></dfn><li><dfn id=webdriver-current-browsing-context><a href=https://w3c.github.io/webdriver/#dfn-current-browsing-context>current browsing context</a></dfn></ul>
   <dt>WebDriver BiDi<dd>
    <p>The following terms are defined in <cite>WebDriver BiDi</cite>: <a href=references.html#refsWEBDRIVERBIDI>[WEBDRIVERBIDI]</a></p>

    <ul class=brief><li><dfn id=webdriver-bidi-navigation-status><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-status>WebDriver BiDi navigation status</a></dfn><li><dfn id=navigation-status-id><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-id>navigation status id</a></dfn><li><dfn id=navigation-status-status><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-status>navigation status status</a></dfn><li><dfn id=navigation-status-canceled><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-canceled>navigation status canceled</a></dfn><li><dfn id=navigation-status-committed><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-committed>navigation status committed</a></dfn><li><dfn id=navigation-status-pending><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-pending>navigation status pending</a></dfn><li><dfn id=navigation-status-complete><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-complete>navigation status complete</a></dfn><li><dfn id=navigation-status-url><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-url>navigation status url</a></dfn><li><dfn id=navigation-status-suggested-filename><a href=https://w3c.github.io/webdriver-bidi/#navigation-status-suggested-filename>navigation status suggested filename</a></dfn><li><dfn id=webdriver-bidi-navigation-aborted><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-aborted>WebDriver BiDi navigation aborted</a></dfn><li><dfn id=webdriver-bidi-navigation-committed><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-committed>WebDriver BiDi navigation committed</a></dfn><li><dfn id=webdriver-bidi-navigation-failed><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-failed>WebDriver BiDi navigation failed</a></dfn><li><dfn id=webdriver-bidi-navigation-started><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigation-started>WebDriver BiDi navigation started</a></dfn><li><dfn id=webdriver-bidi-download-started><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-download-started>WebDriver BiDi download started</a></dfn><li><dfn id=webdriver-bidi-fragment-navigated><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-fragment-navigated>WebDriver BiDi fragment navigated</a></dfn><li><dfn id=webdriver-bidi-dom-content-loaded><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-dom-content-loaded>WebDriver BiDi DOM content loaded</a></dfn><li><dfn id=webdriver-bidi-load-complete><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-load-complete>WebDriver BiDi load complete</a></dfn><li><dfn id=webdriver-bidi-history-updated><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-history-updated>WebDriver BiDi history updated</a></dfn><li><dfn id=webdriver-bidi-navigable-created><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigable-created>WebDriver BiDi navigable created</a></dfn><li><dfn id=webdriver-bidi-navigable-destroyed><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-navigable-destroyed>WebDriver BiDi navigable destroyed</a></dfn><li><dfn id=webdriver-bidi-user-prompt-closed><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-user-prompt-closed>WebDriver BiDi user prompt closed</a></dfn><li><dfn id=webdriver-bidi-user-prompt-opened><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-user-prompt-opened>WebDriver BiDi user prompt opened</a></dfn><li><dfn id=webdriver-bidi-file-dialog-opened><a href=https://w3c.github.io/webdriver-bidi/#webdriver-bidi-file-dialog-opened>WebDriver BiDi file dialog opened</a></dfn></ul>
   <dt>Web Cryptography API<dd>
    <p>The following terms are defined in <cite>Web Cryptography API</cite>:
    <a href=references.html#refsWEBCRYPTO>[WEBCRYPTO]</a></p>

    <ul class=brief><li><dfn id=generating-a-random-uuid><a href=https://w3c.github.io/webcrypto/#dfn-generate-a-random-uuid>generating a random UUID</a></dfn></ul>
   <dt>WebSockets<dd>
    <p>The following terms are defined in <cite>WebSockets</cite>: <a href=references.html#refsWEBSOCKETS>[WEBSOCKETS]</a></p>

    <ul class=brief><li><dfn id=websocket-2><a href=https://websockets.spec.whatwg.org/#websocket><code>WebSocket</code></a></dfn><li><dfn data-dfn-for=WebSocket id=make-disappear><a href=https://websockets.spec.whatwg.org/#make-disappear>make disappear</a></dfn></ul>
   <dt>WebTransport<dd>
    <p>The following terms are defined in <cite>WebTransport</cite>: <a href=references.html#refsWEBTRANSPORT>[WEBTRANSPORT]</a></p>

    <ul class=brief><li><dfn id=webtransport><a href=https://w3c.github.io/webtransport/#webtransport><code>WebTransport</code></a></dfn><li><dfn id=context-cleanup-steps><a href=https://w3c.github.io/webtransport/#context-cleanup-steps><code>context cleanup steps</code></a></dfn></ul>
   <dt>Web Authentication: An API for accessing Public Key Credentials<dd>
    <p>The following terms are defined in <cite>Web Authentication: An API for accessing Public Key
    Credentials</cite>: <a href=references.html#refsWEBAUTHN>[WEBAUTHN]</a></p>

    <ul class=brief><li><dfn id=public-key-credential><a href=https://w3c.github.io/webauthn/#public-key-credential>public key credential</a></dfn></ul>
   <dt>Credential Management<dd>
    <p>The following terms are defined in <cite>Credential Management</cite>: <a href=references.html#refsCREDMAN>[CREDMAN]</a></p>

    <ul class=brief><li><dfn id=conditional-mediation><a href=https://w3c.github.io/webappsec-credential-management/#dom-credentialmediationrequirement-conditional>conditional mediation</a></dfn><li><dfn id=credman-credential><a href=https://w3c.github.io/webappsec-credential-management/#credential>credential</a></dfn><li><dfn id=navigator.credentials.get()><a href=https://w3c.github.io/webappsec-credential-management/#dom-credentialscontainer-get><code>navigator.credentials.get()</code></a></dfn></ul>
   <dt>Console<dd>
    <p>The following terms are defined in <cite>Console</cite>: <a href=references.html#refsCONSOLE>[CONSOLE]</a></p>

    <ul class=brief><li><dfn id=report-a-warning-to-the-console><a href=https://console.spec.whatwg.org/#report-a-warning-to-the-console>report a warning to the console</a></dfn></ul>
   <dt>Web Locks API<dd>
    <p>The following terms are defined in <cite>Web Locks API</cite>: <a href=references.html#refsWEBLOCKS>[WEBLOCKS]</a></p>

    <ul class=brief><li><dfn id=locks><a href=https://w3c.github.io/web-locks/#lock-concept>locks</a></dfn><li><dfn id=lock-requests><a href=https://w3c.github.io/web-locks/#lock-request>lock requests</a></dfn></ul>
   <dt>Trusted Types<dd>
    <p>This specification uses the following features defined in <cite>Trusted Types</cite>:
    <a href=references.html#refsTRUSTED-TYPES>[TRUSTED-TYPES]</a></p>

    <ul class=brief><li><dfn id=tt-trustedhtml><a href=https://w3c.github.io/trusted-types/dist/spec/#trustedhtml><code>TrustedHTML</code></a></dfn><li><dfn id=tt-trustedhtml-data><a href=https://w3c.github.io/trusted-types/dist/spec/#trustedhtml-data>data</a></dfn><li><dfn id=tt-trustedscript><a href=https://w3c.github.io/trusted-types/dist/spec/#trusted-script><code>TrustedScript</code></a></dfn><li><dfn id=tt-trustedscript-data><a href=https://w3c.github.io/trusted-types/dist/spec/#trustedscript-data><code>data</code></a></dfn><li><dfn id=tt-trustedscripturl><a href=https://w3c.github.io/trusted-types/dist/spec/#trustedscripturl><code>TrustedScriptURL</code></a></dfn><li><dfn id=tt-getcompliantstring><a href=https://w3c.github.io/trusted-types/dist/spec/#get-trusted-type-compliant-string-algorithm>Get Trusted Type compliant string</a></dfn></ul>
   <dt>WebRTC API<dd>
    <p>The following terms are defined in <cite>WebRTC API</cite>: <a href=references.html#refsWEBRTC>[WEBRTC]</a></p>

    <ul class=brief><li><dfn id=rtcdatachannel><a href=https://w3c.github.io/webrtc-pc/#dom-rtcdatachannel><code>RTCDataChannel</code></a></dfn><li><dfn id=rtcpeerconnection><a href=https://w3c.github.io/webrtc-pc/#dom-rtcpeerconnection><code>RTCPeerConnection</code></a></dfn></ul>
   <dt>Picture-in-Picture API<dd>
    <p>The following terms are defined in <cite>Picture-in-Picture API</cite>: <a href=references.html#refsPICTUREINPICTURE>[PICTUREINPICTURE]</a></p>

    <ul class=brief><li><dfn id=pictureinpicturewindow><a href=https://w3c.github.io/picture-in-picture/#pictureinpicturewindow><code>PictureInPictureWindow</code></a></dfn></ul>
   <dt>Idle Detection API<dd>
    <p>The following terms are defined in <cite>Idle Detection API</cite>:</p>

    <ul class=brief><li><dfn id=idledetector><a href=https://wicg.github.io/idle-detection/#idledetector><code>IdleDetector</code></a></dfn></ul>
   <dt>Web Speech API<dd>
    <p>The following terms are defined in <cite>Web Speech API</cite>:</p>

    <ul class=brief><li><dfn id=speechrecognition><a href=https://wicg.github.io/speech-api/#speechrecognition><code>SpeechRecognition</code></a></dfn></ul>
   <dt>WebOTP API<dd>
    <p>The following terms are defined in <cite>WebOTP API</cite>:</p>

    <ul class=brief><li><dfn id=otpcredential><a href=https://wicg.github.io/web-otp/#otpcredential><code>OTPCredential</code></a></dfn></ul>
   <dt>Web Share API<dd>
   <p>The following terms are defined in <cite>Web Share API</cite>:</p>

   <ul class=brief><li><dfn id=dom-navigator-share><a href=https://w3c.github.io/web-share/#share-method>share()</a></dfn></ul>
  <dt>Web Smart Card API<dd>
   <p>The following terms are defined in <cite>Web Smart Card API</cite>:</p>

   <ul class=brief><li><dfn id=smartcardconnection><a href=https://wicg.github.io/web-smart-card/#dom-smartcardconnection><code>SmartCardConnection</code></a></dfn></ul>
  <dt>Web Background Synchronization<dd>
   <p>The following terms are defined in <cite>Web Background Synchronization</cite>:</p>

   <ul class=brief><li><dfn id=syncmanager><a href=https://wicg.github.io/background-sync/spec/#syncmanager><code>SyncManager</code></a></dfn><li><dfn id=dom-syncmanager-register><a href=https://wicg.github.io/background-sync/spec/#dom-syncmanager-register><code>register()</code></a></dfn></ul>
  <dt>Web Periodic Background Synchronization<dd>
   <p>The following terms are defined in <cite>Web Periodic Background Synchronization</cite>:</p>

   <ul class=brief><li><dfn id=periodicsyncmanager><a href=https://wicg.github.io/periodic-background-sync/#periodicsyncmanager><code>PeriodicSyncManager</code></a></dfn><li><dfn id=dom-periodicsyncmanager-register><a href=https://wicg.github.io/periodic-background-sync/#dom-periodicsyncmanager-register><code>register()</code></a></dfn></ul>
  <dt>Web Background Fetch<dd>
   <p>The following terms are defined in <cite>Background Fetch</cite>:</p>

   <ul class=brief><li><dfn id=backgroundfetchmanager><a href=https://wicg.github.io/background-fetch/#backgroundfetchmanager><code>BackgroundFetchManager</code></a></dfn><li><dfn id=dom-backgroundfetchmanager-fetch><a href=https://wicg.github.io/background-fetch/#dom-backgroundfetchmanager-fetch><code>fetch()</code></a></dfn></ul>
  <dt>Keyboard Lock<dd>
   <p>The following terms are defined in <cite>Keyboard Lock</cite>:</p>

   <ul class=brief><li><dfn id=keyboard><a href=https://wicg.github.io/keyboard-lock/#keyboard><code>Keyboard</code></a></dfn><li><dfn id=dom-keyboard-lock><a href=https://wicg.github.io/keyboard-lock/#dom-keyboard-lock><code>lock()</code></a></dfn></ul>
  <dt>Web MIDI API<dd>
   <p>The following terms are defined in <cite>Web MIDI API</cite>:</p>

   <ul class=brief><li><dfn id=dom-navigator-requestmidiaccess><a href=https://webaudio.github.io/web-midi-api/#dom-navigator-requestmidiaccess><code>requestMIDIAccess()</code></a></dfn></ul>
  <dt>Generic Sensor API<dd>
   <p>The following terms are defined in <cite>Generic Sensor API</cite>:</p>

   <ul class=brief><li><dfn id=request-sensor-access><a href=https://w3c.github.io/sensors/#request-sensor-access>request sensor access</a></dfn></ul>
  <dt>WebHID API<dd>
   <p>The following terms are defined in <cite>WebHID API</cite>:</p>

   <ul class=brief><li><dfn id=request-device><a href=https://wicg.github.io/webhid/#requestdevice-method><code>requestDevice</code></a></dfn></ul>
  <dt>WebXR Device API<dd>
   <p>The following terms are defined in <cite>WebXR Device API</cite>:</p>

   <ul class=brief><li><dfn id=xrsystem><a href=https://immersive-web.github.io/webxr/#xrsystem><code>XRSystem</code></a></dfn></ul>
  </dl>

  <hr>

  <p>This specification does not <em>require</em> support of any particular network protocol, style
  sheet language, scripting language, or any of the DOM specifications beyond those required in the
  list above. However, the language described by this specification is biased towards CSS as the
  styling language, JavaScript as the scripting language, and HTTP as the network protocol, and
  several features assume that those languages and protocols are in use.</p>

  <p>A user agent that implements the HTTP protocol must implement <cite>HTTP State Management
  Mechanism</cite> (Cookies) as well. <a href=references.html#refsHTTP>[HTTP]</a> <a href=references.html#refsCOOKIES>[COOKIES]</a></p>

  <p class=note>This specification might have certain additional requirements on character
  encodings, image formats, audio formats, and video formats in the respective sections.</p>

  </div>




  <h4 id=extensibility-2><span class=secno>2.1.10</span> Extensibility<a href=#extensibility-2 class=self-link></a></h4>

  <p>Vendor-specific proprietary user agent extensions to this specification are strongly
  discouraged. Documents must not use such extensions, as doing so reduces interoperability and
  fragments the user base, allowing only users of specific user agents to access the content in
  question.</p>

  

  <p>All extensions must be defined so that the use of extensions neither contradicts nor causes the
  non-conformance of functionality defined in the specification.</p> 

  <div class=example>

   <p>For example, while strongly discouraged from doing so, an implementation could add a new IDL
   attribute "<code>typeTime</code>" to a control that returned the time it took the user
   to select the current value of a control (say). On the other hand, defining a new control that
   appears in a form's <code id=extensibility-2:dom-form-elements><a href=forms.html#dom-form-elements>elements</a></code> array would be in violation
   of the above requirement, as it would violate the definition of <code id=extensibility-2:dom-form-elements-2><a href=forms.html#dom-form-elements>elements</a></code> given in this specification.</p>

  </div>

  

  <hr>

  <p>When vendor-neutral extensions to this specification are needed, either this specification can
  be updated accordingly, or an extension specification can be written that overrides the
  requirements in this specification. When someone applying this specification to their activities
  decides that they will recognize the requirements of such an extension specification, it becomes
  an <dfn id=other-applicable-specifications>applicable specification</dfn> for the purposes
  of conformance requirements in this specification.</p>

  <p class=note>Someone could write a specification that defines any arbitrary byte stream as
  conforming, and then claim that their random junk is conforming. However, that does not mean that
  their random junk actually is conforming for everyone's purposes: if someone else decides that
  that specification does not apply to their work, then they can quite legitimately say that the
  aforementioned random junk is just that, junk, and not conforming at all. As far as conformance
  goes, what matters in a particular community is what that community <em>agrees</em> is
  applicable.</p>

  

  <hr>

  <p>User agents must treat elements and attributes that they do not understand as semantically
  neutral; leaving them in the DOM (for DOM processors), and styling them according to CSS (for CSS
  processors), but not inferring any meaning from them.</p>

  <p>When support for a feature is disabled (e.g. as an emergency measure to mitigate a security
  problem, or to aid in development, or for performance reasons), user agents must act as if they
  had no support for the feature whatsoever, and as if the feature was not mentioned in this
  specification. For example, if a particular feature is accessed via an attribute in a Web IDL
  interface, the attribute itself would be omitted from the objects that implement that interface
  — leaving the attribute on the object but making it return null or throw an exception is
  insufficient.</p>

  


  

  <h4 id=interactions-with-xpath-and-xslt><span class=secno>2.1.11</span> Interactions with XPath and XSLT<a href=#interactions-with-xpath-and-xslt class=self-link></a></h4>

  <p id=xpath-1.0-processors>Implementations of XPath 1.0 that operate on <a id=interactions-with-xpath-and-xslt:html-documents href=https://dom.spec.whatwg.org/#html-document data-x-internal=html-documents>HTML
  documents</a> parsed or created in the manners described in this specification (e.g. as part of
  the <code>document.evaluate()</code> API) must act as if the following edit was applied
  to the XPath 1.0 specification.</p>

  <p>First, remove this paragraph:</p>

  <blockquote cite=https://www.w3.org/TR/1999/REC-xpath-19991116/#node-tests>

   <p>A <a href=https://www.w3.org/TR/REC-xml-names/#NT-QName>QName</a> in the node test is expanded
   into an <a href=https://www.w3.org/TR/1999/REC-xpath-19991116/#dt-expanded-name>expanded-name</a>
   using the namespace declarations from the expression context. This is the same way expansion is
   done for element type names in start and end-tags except that the default namespace declared with
   <code>xmlns</code> is not used: if the <a href=https://www.w3.org/TR/REC-xml-names/#NT-QName>QName</a> does not have a prefix, then the
   namespace URI is null (this is the same way attribute names are expanded). It is an error if the
   <a href=https://www.w3.org/TR/REC-xml-names/#NT-QName>QName</a> has a prefix for which there is
   no namespace declaration in the expression context.</p>

  </blockquote>

  <p>Then, insert in its place the following:</p>

  <blockquote cite="https://www.w3.org/Bugs/Public/show_bug.cgi?id=7059#c37">

   <p>A QName in the node test is expanded into an expanded-name using the namespace declarations
   from the expression context. If the QName has a prefix, then there must be a namespace declaration for this prefix in
   the expression context, and the corresponding namespace URI is the one that is
   associated with this prefix. It is an error if the QName has a prefix for which there is no
   namespace declaration in the expression context. </p>

   <p>If the QName has no prefix and the principal node type of the axis is element, then the
   default element namespace is used. Otherwise, if the QName has no prefix, the namespace URI is
   null. The default element namespace is a member of the context for the XPath expression. The
   value of the default element namespace when executing an XPath expression through the DOM3 XPath
   API is determined in the following way:</p>

   <ol><li>If the context node is from an HTML DOM, the default element namespace is
    "http://www.w3.org/1999/xhtml".<li>Otherwise, the default element namespace URI is null.</ol>

   <p class=note>This is equivalent to adding the default element namespace feature of XPath 2.0
   to XPath 1.0, and using the HTML namespace as the default element namespace for HTML documents.
   It is motivated by the desire to have implementations be compatible with legacy HTML content
   while still supporting the changes that this specification introduces to HTML regarding the
   namespace used for HTML elements, and by the desire to use XPath 1.0 rather than XPath 2.0.</p>

  </blockquote>

  <p class=note>This change is a <a id=interactions-with-xpath-and-xslt:willful-violation href=https://infra.spec.whatwg.org/#willful-violation data-x-internal=willful-violation>willful violation</a> of the XPath 1.0 specification,
  motivated by desire to have implementations be compatible with legacy content while still
  supporting the changes that this specification introduces to HTML regarding which namespace is
  used for HTML elements. <a href=references.html#refsXPATH10>[XPATH10]</a></p> 

  <hr>

  <p id=dom-based-xslt-1.0-processors>XSLT 1.0 processors outputting to a DOM when the output
  method is "html" (either explicitly or via the defaulting rule in XSLT 1.0) are affected as
  follows:</p>

  <p>If the transformation program outputs an element in no namespace, the processor must, prior to
  constructing the corresponding DOM element node, change the namespace of the element to the
  <a id=interactions-with-xpath-and-xslt:html-namespace-2 href=https://infra.spec.whatwg.org/#html-namespace data-x-internal=html-namespace-2>HTML namespace</a>, <a href=https://infra.spec.whatwg.org/#ascii-lowercase id=interactions-with-xpath-and-xslt:converted-to-ascii-lowercase data-x-internal=converted-to-ascii-lowercase>ASCII-lowercase</a> the
  element's local name, and <a href=https://infra.spec.whatwg.org/#ascii-lowercase id=interactions-with-xpath-and-xslt:converted-to-ascii-lowercase-2 data-x-internal=converted-to-ascii-lowercase>ASCII-lowercase</a> the
  names of any non-namespaced attributes on the element.</p>

  <p class=note>This requirement is a <a id=interactions-with-xpath-and-xslt:willful-violation-2 href=https://infra.spec.whatwg.org/#willful-violation data-x-internal=willful-violation>willful violation</a> of the XSLT 1.0
  specification, required because this specification changes the namespaces and case-sensitivity
  rules of HTML in a manner that would otherwise be incompatible with DOM-based XSLT
  transformations. (Processors that serialize the output are unaffected.) <a href=references.html#refsXSLT10>[XSLT10]</a></p> 

  <hr>

  <p>This specification does not specify precisely how XSLT processing interacts with the <a id=interactions-with-xpath-and-xslt:html-parser href=parsing.html#html-parser>HTML
  parser</a> infrastructure (for example, whether an XSLT processor acts as if it puts any
  elements into a <a id=interactions-with-xpath-and-xslt:stack-of-open-elements href=parsing.html#stack-of-open-elements>stack of open elements</a>). However, XSLT processors must <a id=interactions-with-xpath-and-xslt:stop-parsing href=parsing.html#stop-parsing>stop
  parsing</a> if they successfully complete, and must <a id=interactions-with-xpath-and-xslt:update-the-current-document-readiness href=dom.html#update-the-current-document-readiness>update the current document
  readiness</a> first to "<code>interactive</code>" and then to "<code>complete</code>" if they are aborted.</p>

  <hr>

  <p>This specification does not specify how XSLT interacts with the <a href=browsing-the-web.html#navigate id=interactions-with-xpath-and-xslt:navigate>navigation</a> algorithm, how it fits in with the <a id=interactions-with-xpath-and-xslt:event-loop href=webappapis.html#event-loop>event loop</a>, nor
  how error pages are to be handled (e.g. whether XSLT errors are to replace an incremental XSLT
  output, or are rendered inline, etc.).</p>

  <p class=note>There are also additional non-normative comments regarding the interaction of XSLT
  and HTML <a href=scripting.html#scriptTagXSLT>in the <code>script</code> element section</a>, and of
  XSLT, XPath, and HTML <a href=scripting.html#template-XSLT-XPath>in the <code>template</code> element
  section</a>.</p>

  



  <h3 id=policy-controlled-features><span class=secno>2.2</span> Policy-controlled features<a href=#policy-controlled-features class=self-link></a></h3><div class="mdn-anno wrapped"><button onclick=toggleStatus(this) class=mdn-anno-btn><b title="Support in one engine only." class=less-than-two-engines-flag>⚠</b><span>MDN</span></button><div class=feature><p><a href=https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Permissions-Policy/document-domain title="The HTTP Permissions-Policy header document-domain directive controls whether the current document is allowed to set document.domain.">Headers/Permissions-Policy/document-domain</a><p class=less-than-two-engines-text>Support in one engine only.<div class=support><span class="firefox yes"><span>Firefox</span><span title="Requires setting a user preference or runtime flag.">🔰 74+</span></span><span class="safari no"><span>Safari</span><span>No</span></span><span class="chrome yes"><span>Chrome</span><span title="Requires setting a user preference or runtime flag.">🔰 88+</span></span><hr><span class="opera unknown"><span>Opera</span><span>?</span></span><span class="edge_blink yes"><span>Edge</span><span title="Requires setting a user preference or runtime flag.">🔰 88+</span></span><hr><span class="edge unknown"><span>Edge (Legacy)</span><span>?</span></span><span class="ie no"><span>Internet Explorer</span><span>No</span></span><hr><span class="firefox_android unknown"><span>Firefox Android</span><span>?</span></span><span class="safari_ios unknown"><span>Safari iOS</span><span>?</span></span><span class="chrome_android no"><span>Chrome Android</span><span>No</span></span><span class="webview_android unknown"><span>WebView Android</span><span>?</span></span><span class="samsunginternet_android unknown"><span>Samsung Internet</span><span>?</span></span><span class="opera_android unknown"><span>Opera Android</span><span>?</span></span></div></div></div>

  <p>This document defines the following <a href=https://w3c.github.io/webappsec-feature-policy/#policy-controlled-feature id=policy-controlled-features:concept-policy-controlled-feature data-x-internal=concept-policy-controlled-feature>policy-controlled features</a>:</p>

  <div class="mdn-anno wrapped before"><button onclick=toggleStatus(this) class=mdn-anno-btn><span>MDN</span></button><div class=feature><p><a href=https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Feature-Policy/autoplay title="The HTTP Permissions-Policy header autoplay directive controls whether the current document is allowed to autoplay media requested through the HTMLMediaElement interface.">Headers/Feature-Policy/autoplay</a><div class=support><span class="firefox yes"><span>Firefox</span><span title="Requires setting a user preference or runtime flag.">🔰 74+</span></span><span class="safari no"><span>Safari</span><span>No</span></span><span class="chrome yes"><span>Chrome</span><span>64+</span></span><hr><span class="opera unknown"><span>Opera</span><span>?</span></span><span class="edge_blink yes"><span>Edge</span><span>79+</span></span><hr><span class="edge unknown"><span>Edge (Legacy)</span><span>?</span></span><span class="ie no"><span>Internet Explorer</span><span>No</span></span><hr><span class="firefox_android unknown"><span>Firefox Android</span><span>?</span></span><span class="safari_ios unknown"><span>Safari iOS</span><span>?</span></span><span class="chrome_android unknown"><span>Chrome Android</span><span>?</span></span><span class="webview_android unknown"><span>WebView Android</span><span>?</span></span><span class="samsunginternet_android unknown"><span>Samsung Internet</span><span>?</span></span><span class="opera_android unknown"><span>Opera Android</span><span>?</span></span></div></div><div class=feature><p><a href=https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Permissions-Policy/autoplay title="The HTTP Permissions-Policy header autoplay directive controls whether the current document is allowed to autoplay media requested through the HTMLMediaElement interface.">Headers/Permissions-Policy/autoplay</a><p class=less-than-two-engines-text>Support in one engine only.<div class=support><span class="firefox yes"><span>Firefox</span><span title="Requires setting a user preference or runtime flag.">🔰 74+</span></span><span class="safari no"><span>Safari</span><span>No</span></span><span class="chrome yes"><span>Chrome</span><span>88+</span></span><hr><span class="opera unknown"><span>Opera</span><span>?</span></span><span class="edge_blink yes"><span>Edge</span><span>88+</span></span><hr><span class="edge unknown"><span>Edge (Legacy)</span><span>?</span></span><span class="ie no"><span>Internet Explorer</span><span>No</span></span><hr><span class="firefox_android unknown"><span>Firefox Android</span><span>?</span></span><span class="safari_ios unknown"><span>Safari iOS</span><span>?</span></span><span class="chrome_android unknown"><span>Chrome Android</span><span>?</span></span><span class="webview_android unknown"><span>WebView Android</span><span>?</span></span><span class="samsunginternet_android unknown"><span>Samsung Internet</span><span>?</span></span><span class="opera_android unknown"><span>Opera Android</span><span>?</span></span></div></div></div><ul><li>"<dfn id=autoplay-feature><code>autoplay</code></dfn>", which has a <a href=https://w3c.github.io/webappsec-feature-policy/#default-allowlist id=policy-controlled-features:concept-default-allowlist data-x-internal=concept-default-allowlist>default allowlist</a> of <code>'self'</code>.<li>"<dfn id=cross-origin-isolated-feature><code>cross-origin-isolated</code></dfn>", which has a <a href=https://w3c.github.io/webappsec-feature-policy/#default-allowlist id=policy-controlled-features:concept-default-allowlist-2 data-x-internal=concept-default-allowlist>default allowlist</a> of <code>'self'</code>.<li>"<dfn id=focus-without-user-activation-feature><code>focus-without-user-activation</code></dfn>", which has a <a href=https://w3c.github.io/webappsec-feature-policy/#default-allowlist id=policy-controlled-features:concept-default-allowlist-3 data-x-internal=concept-default-allowlist>default allowlist</a> of <code>'self'</code>.</ul>


  <nav><a href=introduction.html>← 1 Introduction</a> — <a href=index.html>Table of Contents</a> — <a href=common-microsyntaxes.html>2.3 Common microsyntaxes →</a></nav>
